U.S. patent application number 09/794762 was filed with the patent office on 2001-10-04 for method for the preparation of citalopram.
This patent application is currently assigned to H. Lundbeck A/S. Invention is credited to Ahmadian, Haleh, Petersen, Hans, Rock, Michael Harold.
Application Number | 20010027256 09/794762 |
Document ID | / |
Family ID | 26068779 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010027256 |
Kind Code |
A1 |
Petersen, Hans ; et
al. |
October 4, 2001 |
Method for the preparation of citalopram
Abstract
The present invention relates to a method for the preparation of
citalopram comprising reaction a compound of formula (I) 1 with a
compound having the formula 2 wherein X is a suitable leaving group
and R is --CH.sub.2--O--Pg, --CH.sub.2--NPg.sub.1P.sub.g2,
--CH--N(CH.sub.3).sub.2, --CH(OR.sup.1)(OR.sup.2)
--C(OR.sup.4)(OR.sup.5)(OR.sup.6), --COOR.sup.3,
--CH.sub.2--CO--NH.sub.2, --CH.dbd.CHR.sup.7 and --CONHR.sup.8,
wherein Pg is a protection group for an alcohol group, Pg.sub.1 and
Pg.sub.2 are protection groups for an amino group, R.sup.1 and
R.sup.2 are independently selected from alkyl, alkenyl, alkynyl and
optionally alkyl substituted aryl or aralkyl groups or R.sup.1 and
R.sup.2 together form a chain of 2 to 4 carbon atoms, each of
R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are independently
selected from alkyl, alkenyl, alkynyl and optionally alkyl
substituted aryl or aralkyl and R.sup.8 is hydrogen or methyl; to
form a compound of the formula 3 wherein R is as defined above;
followed by conversion of the group R to form a dimethylaminomethyl
group and isolation of citalopram base or a pharmaceutically
acceptable salt thereof.
Inventors: |
Petersen, Hans; (Vanlose,
DK) ; Rock, Michael Harold; (Hvidovre, DK) ;
Ahmadian, Haleh; (Solrod Strand, DK) |
Correspondence
Address: |
DARBY & DARBY P.C.
805 Third Avenue
New York
NY
10022
US
|
Assignee: |
H. Lundbeck A/S
Copenhagen
DK
|
Family ID: |
26068779 |
Appl. No.: |
09/794762 |
Filed: |
February 26, 2001 |
Current U.S.
Class: |
549/462 |
Current CPC
Class: |
A61P 25/24 20180101;
C07D 307/87 20130101; A61K 31/343 20130101 |
Class at
Publication: |
549/462 |
International
Class: |
C07D 307/87 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 24, 2000 |
DK |
PA 2000 00296 |
Mar 13, 2000 |
DK |
PA 2000 00401 |
Claims
1. A method for the preparation of citalopram comprising reacting a
compound of formula (I) 20with a compound having the formula
21wherein X is a suitable leaving group and R is --CH.sub.2--O--Pg,
--CH.sub.2--NPg.sub.1Pg.sub.2, --CH.sub.2--NMePg.sub.1,
--CO--N(CH.sub.3).sub.2, --CH(OR.sup.1)(OR.sup.2),
--C(OR.sup.4)(OR.sup.5)(OR.sup.6), --COOR.sup.3,
--CH.sub.2--CO--NH.sub.2- , --CH.dbd.CHR.sup.7 or --CO--NHR.sup.8,
wherein Pg is a protection group for an alcohol group, Pg.sub.1 and
Pg.sub.2 are protection groups for an amino group, R.sup.1 and
R.sup.2 are independently selected from alkyl, alkenyl, alkynyl and
optionally alkyl substituted aryl or aralkyl groups or R.sup.1 and
R.sup.2 together form a chain of 2 to 4 carbon atoms, each of
R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are independently
selected from alkyl, alkenyl, alkynyl and optionally alkyl
substituted aryl or aralkyl and R.sup.8 is hydrogen or methyl; to
form a compound of the formula 22wherein R is as defined above;
followed by conversion of the group R to form a dimethylaminomethyl
group and isolation of citalopram base or a pharmaceutically
acceptable salt thereof.
2. The method according to claim 1 wherein the compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--CH.sub.2--O--Pg followed by removal of the protection group to
form the corresponding alcohol of the formula 23and thereafter
conversion of the alcohol group to a feasible leaving group and
reaction of the resulting compound a) with dimethylamine or a metal
salt thereof to form citalopram, b) with methylamine followed by
reductive amination to form citalopram, or c) with an azide
followed by reduction to form the corresponding amino compound and
thereafter methylation or reductive amination to form
citalopram.
3. The method according to claim 1 wherein the compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--CO--N(CH.sub.3).sub.2, followed by reduction of the resulting
compound of the formula 24to form citalopram.
4. The method according to claim 1 wherein the compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--CH.sub.2--N(Pg.sub.1)(Pg.sub.2) followed by removal of the
protection groups to form a compound of formula 25and thereafter
reductive amination or methylation of the free amino group to form
citalopram.
5. The method according to claim I wherein a compound of formula
(II) is reacted with a compound of formula (11) wherein R is
--CH(OR.sup.1)(OR.sup.2) or --C(OR.sup.4)(OR.sup.5)(OR.sup.6) to
form a compound of the formula (VIIa) or (VIIb) 26wherein R.sup.1,
R.sup.2, R.sup.4, R.sup.5 and R.sup.6 are as defined above,
followed by deprotection of the compound of formula (VIIa) or
(VIIb) and consecutive reductive amination of the resulting
aldehyde to form citalopram.
6. The method according to claim 1 wherein a compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--COOR.sup.3 to form a compound of the formula 27which is converted
to an amide of formula (V) followed by reduction to form
citalopram, or the compound of formula (VIII) is reduced to form
the corresponding alcohol of formula (IV) followed by conversion of
the alcohol group to feasible leaving group and consecutively
reaction a) with dimethylamine or a metal salt thereof to form
citalopram, b) with methylamine followed by reductive amination to
form citalopram, or c) with an azide followed by reduction to form
the corresponding amino compound and thereafter methylation or
reductive amination to form citalopram.
7. The method according to claim 1 wherein a compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--CH.sub.2--CONH.sub.2 to form a compound of formula 28which is
treated with hypohalide to form a compound of formula 29followed by
methylation of the free amino group or reductive amination to form
citalopram.
8. The method according to claim I wherein a compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--CH.dbd.CHR.sup.7 to form a compound of formula 30wherein R.sup.7
is as defined above, which is oxidised to form a compound of
formula 31followed by reductive amination to form citalopram.
9. The method according to claim 1 wherein the compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--CH.sub.2--Me(Pg.sub.1) followed by removal of the protection
group to form a compound of formula 32and thereafter methylation of
the amino group or reductive amination to form citalopram.
10. The method according to claim 1 wherein the compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--CO--NHR.sup.8 wherein R.sup.8 is hydrogen or methyl, followed by
reduction of the resulting compound of the formula 33wherein
R.sup.8 is as defined above, to form a compound of formula
34wherein R.sup.8 is as defined above, followed by methylation or
reductive amination to form citalopram.
11. The method according to claim 1 wherein the reaction of the
compound of formula (I) with a compound of formula (II) is carried
out in presence of a base selected from LDA
(lithiumdiisopropylamine), LiHMDS (hexamethyldisilasan lithium),
NaH, NaHMDS (hexamethyldisilasan sodium) and a metalalkoxide.
12. The method of claim 1, wherein said metalalkoxide is selected
from the group consisting of NaOMe, KOMe, LiOMe, NaOtertBu,
KOtertBu and LiOtertBu.
13. An antidepressant pharmaceutical composition comprising
citalopram manufactured by the process of any of claims 1 to
11.
14. A compound having the general formula 35wherein R is
--CH.sub.2--O--Pg, --CH.sub.2--NPg.sub.1Pg.sub.2,
--CH.sub.2--NMePg.sub.1- , --CO--N(CH.sub.3).sub.2,
--CH(OR.sup.1)(OR.sup.2), --C(O.sup.4)(OR.sup.5)(OR.sup.6),
--COOR.sup.3, --CH.sub.2CO--NH.sub.2, --CH.dbd.CHR.sup.7 or
--CO--NHR.sup.8, wherein Pg is a protection group for an alcohol
group, Pg.sub.1 and Pg.sub.2 are protection groups for an amino
group, R.sup.1 and R.sup.2 are independently selected from alkyl,
alkenyl, alkynyl and optionally alkyl substituted aryl or aralkyl
groups or R.sup.1 and R.sup.2 together form a chain of 2 to 4
carbon atoms, each of R.sup.3, R.sup.4, R.sup.5, R.sup.6 and
R.sup.7 are ndependently selected from alkyl, alkenyl, alkynyl and
optionally alkyl substituted aryl or aralkyl and R.sup.8 is
hydrogen or methyl, and acid addition salts thereof.
15. A compound intermediate having the formula 36and acid addition
salts thereof.
16. A compound having the formula 37and acid addition salts
thereof.
17. A compound having the formula 38and acid addition salts
thereof.
18. A compound having the formula 39and acid addition salts
thereof.
Description
[0001] The present invention relates to a method for the
preparation of the well-known antidepressant drug
citalopram,1-[3-(dimethylamino)propyl]-
-1-(4fluorophenyl)-1,3dihydro-5-isobenzofurancarbonitrile.
BACKGROUND OF THE INVENTION
[0002] Citalopram is a well-known antidepressant drug that has now
been on the market for some years and has the following structure:
4
[0003] It is a selective, centrally acting serotonin
(5-hydroxytryptamine; 5-HT) reuptake inhibitor, accordingly having
antidepressant activities. The antidepressant activity of the
compound has been reported in several publications, eg. J. Hyttel
Prog. Neuro-Psychopharmacol. & Biol. Psychiat. 1982, 6, 277-295
and A. Gravem Acta Psychiatr. Scand. 1987, 75, 478-486. The
compound has further been disclosed to show effects in the
treatment of dementia and cerebrovascular disorders,
EP-A-474580.
[0004] Citalopram was first disclosed in DE 2,657,013 ,
corresponding to U.S. Pat No. 4,136,193. This patent publication
describes the preparation of citalopram by one method and outlines
a further method which may be used for preparing citalopram.
[0005] According to the process described, the corresponding
1-(4fluorophenyl)-1,3dihydro-5-isobenzofurancarbonitrile is reacted
with 3(N,N-dimethylamino)propyl-chloride in the presence of
methylsulfinylmethide as condensing agent. The starting material
was prepared from the corresponding 5-bromo derivative by reaction
with cuprous cyanide.
[0006] International patent application No. WO 98/019511 discloses
a process for the manufacture of citalopram wherein a (4- (cyano,
alkyloxycarbonyl or
alkylamninocarbonyl)-2-hydroxymethylphenyl-(4-fluorop-
henyl)methanol compound is subjected to ring closure. The resulting
5-(alkyloxycarbonyl or
alkylaminocarbonyl)-1-(4fluorophenyl)-1,3-dihydroi- sobenzofuran is
converted to the corresponding 5-cyano derivative and the 5-cyano
derivative is then alkylated with a (3-dimethylamino)propylhaloge-
nide in order to obtain citalopram.
[0007] It has now, surprisingly, been found that citalopram may be
manufactured by a novel favourable process where
5-cyano-1-(4-fluoropheny- l)-1,3-dihydroisobenzofuran is alkylated
with a compound which may be converted to a dimethylaminopropyl
group.
[0008] The alkylation process according to the invention is
particularly advantageous because the formation of by-products by
polymerisation of the alkylating agent is avoided whereby a
reduction in the amount of alkylating reagent used is made
possible. In addition, the process of the invention provides high
yields.
SUMMARY OF THE INVENTION
[0009] The present invention relates to a method for the
preparation of citalopram comprising reaction of a compound of
formula (I) 5
[0010] with a compound having the formula 6
[0011] wherein X is a suitable leaving group and R is
--CH.sub.2--O--Pg, --CH.sub.2--NPg.sub.1Pg.sub.2,
--CH.sub.2--NMePg.sub.1, --CO--N(CH.sub.3).sub.2,
--CH(OR.sup.1)(OR.sup.2), --C(OR.sup.4)(OR.sup.5)(OR.sup.6),
COOR.sup.3, CH.sub.2--CO--NH.sub.2, --CH.dbd.CHR.sup.7 or
--CO--NHR.sup.8 wherein Pg is a protection group for an alcohol
group, Pg.sub.1 and Pg.sub.2 are protection groups for an amino
group, R.sup.1 and R.sup.2 are independently selected from alkyl,
alkenyl, alkynyl and optionally alkyl substituted aryl or aralkyl
groups or R.sup.1 and R.sup.2 together form a chain of 2 to 4
carbon atoms, R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are
independently selected from alkyl, alkenyl, alkynyl and optionally
alkyl substituted aryl or aralkyl and R.sup.8 is hydrogen or
methyl; to form a compound of the formula 7
[0012] wherein R is as defined above; followed by conversion of the
group R to a dimethylaminomethyl group and isolation of citalopram
in the form of the base or as a pharmaceutically acceptable salt
thereof.
[0013] In a first embodiment of the invention, the compound of
formula (I) is reacted with a compound of formula (II) wherein R is
--CH.sub.2--O--Pg, wherein Pg is a protection group for an alcohol
group, followed by removal of the protection group to form the
corresponding alcohol of the formula 8
[0014] The alcohol group is then converted to a feasible leaving
group such as halogen or --O--SO.sub.2--R.sup.0 wherein R.sup.0 is
alkyl, or optionally alkyl substituted aryl or aralkyl, and the
resulting compound is then
[0015] a) reacted with dimethylamin or a metal salt thereof to form
citalopram,
[0016] b) reacted with methylamin to form a compound of formula
(XII) below followed by reductive amination to form citalopram,
or
[0017] c) reacted with an azide followed by reduction to form the
corresponding amino compound of formula (VI) below and thereafter
methylation or reductive amination to form citalopram.
[0018] In a second embodiment, the compound of formula (I) is
reacted with a compound of formula (II) wherein R is
--CO--N(CH.sub.3).sub.2, followed by reduction of the resulting
compound of the formula 9
[0019] to form citalopram.
[0020] In a third embodiment, the compound of formula (I) is
reacted with a compound of formula (II) wherein R is
--CH.sub.2--N(Pg.sub.1)(Pg.sub.2) where Pg.sub.1 or Pg.sub.2 are
protection groups for an amino group and thereafter removal of the
protection groups to form a compound of formula 10
[0021] followed by methylation of the free amino group or reductive
amination to form citalopram.
[0022] In a fourth embodiment, citalopram may be prepared by
reaction of a compound of formula (I) with a compound of formula
(II) wherein R is --CH(OR.sup.1)(OR.sup.2) or
--C(OR.sup.4)(OR.sup.5)(OR.sup.6) where R.sup.1, R.sup.2, R.sub.4
R.sup.5 and R.sup.6 are as defined above to form a compound of the
formula (VIIa) or (VIIb) 11
[0023] wherein R.sup.1, R.sup.2, R.sup.4, R.sup.5 and R.sup.6 are
as defined above, followed by deprotection of the compound of
formula (VIIa) or (VIIb) and consecutively reductive amination of
the resulting aldehyde with dimethylamin to form citalopram.
[0024] In a fifth embodiment, citalopram may be prepared by
reaction of a compound of formula (I) with a compound of formula
(II) wherein R is --COOR.sup.3 and R.sup.3 is as defined above to
form a compound of the formula 12
[0025] wherein R.sup.3 is as defined above, which is then converted
to an amide of formula (V) or an alcohol of formula (IV) which is
converted to citalopram as described above.
[0026] In a sixth embodiment, the invention relates to a method for
the preparation of citalopram wherein a compound of formula (I) is
reacted with a compound of formula (II) wherein R is
--CH.sub.2--CONH.sub.2 to form a compound of formula 13
[0027] which is treated with hypohalide to form a compound of
formula 14
[0028] followed by methylation of the free amino group or reductive
amination to form citalopram.
[0029] In a seventh embodiment, the invention relates to a method
for the preparation of citalopram by reaction of a compound of
formula (I) with a compound of formula (II) wherein R is
--CH.dbd.CHR.sup.7 to form a compound of formula 15
[0030] wherein R.sup.7 is as defined above, which is oxidised to
form a compound of formula 16
[0031] followed by reductive amination with dimethylamin to form
citalopram.
[0032] In a eight embodiment, the invention relates to a process
for the preparation of citalopram wherein the compound of formula
(I) is reacted with a compound of formula (II) wherein R is
--CH.sub.2--Me(Pg.sub.1) followed by removal of the protection
group to form a compound of formula 17
[0033] and thereafter methylation of the amino group or reductive
amination to form citalopram.
[0034] In a final embodiment, the invention relates to a method for
the preparation of citalopram wherein the compound of formula (I)
is reacted with a compound of formula (II) wherein R is
--CO--NHR.sup.8 wherein R.sup.8 is hydrogen or methyl, followed by
reduction of the resulting compound of the formula 18
[0035] wherein R.sup.8 is as defined above, to form a compound of
formula 19
[0036] wherein R.sup.8 is as defined above, followed by methylation
or reductive amination to form citalopram.
[0037] In another aspect, the present invention provides the novel
intermediates of the general formula (III), (IV), (VI), (XI) and
(XII).
[0038] In yet another aspect, the present invention relates to an
antidepressant pharmaceutical composition comprising citalopram
manufactured by the process of the invention.
[0039] The alkylation step where the compound of formula (I) is
reacted with a compound of formula (II) is suitably carried out by
treatment of the compound of formula (I) with a base such as for
example LDA ( lithiumdiisopropylamine), LiHMDS (hexamethyldisilasan
lithium), NaH, NaHMDS (hexamethyldisilasan sodium) and
metalalkoxides such as NaOMe, KOMe, LiOMe, NaOtertBu, KOtertBu and
LiOtertBu in an aprotic organic solvent such as THF
(tetrahydrofurane), DMF (dimethylformamide), NMP
(N-methylpyrrolidon), ethers such as diethylether or dioxalane,
toluene, benzene, or alkanes and mixtures thereof. The anion formed
is then reacted with a compound of formula (II) whereby a group of
formula --CH.sub.2--CH.sub.2--R is introduced into position 1 of
the isobenzofuranyl ring system.
[0040] Leaving groups X, may be a halogenide or a sulphonate of
formula --O--SO.sub.2--R.sup.0 wherein R.sup.0 is alkyl, or
optionally alkyl substituted aryl or aralkyl. Suitably, R.sup.0 is
methyl or p-methylphenyl.
[0041] The substituents R.sup.1 and R.sup.2 are preferably alkyl,
or aralkyl or R.sup.1 and R.sup.2 together form a chain of 2 to 4
carbon atoms. Suitably, R.sup.1 and R.sup.2 are identical.
[0042] The substituents R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are
preferably alkyl, or aralkyl. Suitably, R.sup.4, R.sup.5 and
R.sup.6 are identical.
[0043] R.sup.7 is preferably alkyl or aralkyl.
[0044] The alcohol protecting group Pg may be a trialkylsilyl
group, a benzyl group or a tetrahydropyranyl group (THP).
[0045] According to the invention, the alcohol protecting group is
removed to form the compound of formula (IV) using conventional
methods for removal of the protection group in question.
[0046] Thus, where the protecting group is trialkylsilyl the
protecting group may be removed by treatment with a base, an
organic or mineral acid or a flouride such as KF or
trialkylaminoflouride.
[0047] Where Pg is benzyl, the protecting group may be removed by
reduction using Pd/C or Pt/C as a catalyst.
[0048] Where Pg is a tetrahydropyranyl (THP) group, the protecting
group may be removed by treatment with an organic or mineral acid,
or resins carrying H.sup.+ groups such as Dowex H.sup.+ or
Amberlyst.
[0049] The alcohol group in the compound of formula (IV) is
converted to a feasible leaving group such as halogen, or a
sulphonate of formula --O--SO.sub.2--R.sup.0 wherein R.sup.0 is as
defined above, by reaction with reagents such as thionylchloride,
mesylchloride, tosylchloride, etc.
[0050] The resulting compound is then reacted with dimethylamin or
a metal salt thereof, e.g. M.sup.+, .sup.-N(CH.sub.3).sub.2 wherein
M.sup.+ is Li.sup.- or Na.sup.+. The reaction is suitably carried
out in an aprotic organic solvent such as THF (tetrahydrofurane),
DMF (dimethylformamide), NMP (N-methyl pyrrolidon), ethers such as
diethylether, or dioxalane, toluene, benzene, or alkanes and
mixtures thereof. The compound of formula (IV) carrying a suitable
leaving group may also be converted to citalopram by reaction with
dimethylammonium chloride in presence of a base. Alternatively, the
compound of formula (IV) carrying a suitable leaving group, such as
a sulphonate of formula --O--SO.sub.2--R.sup.6 wherein R.sup.0 is
as defined above, may be reacted with an azide, such as sodium
azide, followed by reduction using Pd/C as a catalyst to form a
compound of formula (VI) and thereafter methylation or reductive
amination to form Citalopram.
[0051] The compound of formula (IV) carrying a suitable leaving
group, may also be converted to citalopram by reaction with
methylamine to form a compound of formula (XII) above, followed by
methylation or reductive amination to form Citalopram.
[0052] The reduction of the amide of formula (V) is conveniently
carried out in toluene using Red-Al as a reducing agent.
[0053] Suitable groups Pg.sub.1 and Pg.sub.2 are aralkyl or
--O--SO.sub.2--R.sup.6 groups wherein R.sup.0 is as defined above,
typically benzyl or tosyl, or Pg.sub.1 and Pg.sub.2 together with
the N atom to which they are attached form an optionally
substituted phthalimide group.
[0054] The protecting groups, Pg.sub.1 and Pg.sub.2 may be removed
using conventional methods for removal of such protective groups.
The phthalimide groups may thus be converted to an amino group by
treatment with hydrazin or methylamine and ethanol.
[0055] Where the protecting group is an aralkyl group, such as
benzyl, it may be removed by reduction, typically in presence of
Pd/C or Pt/C as a catalyst.
[0056] The sulphonate groups of formula --O--SO.sub.2--R.sup.0 may
be removed by treatment with Red-Al.
[0057] The free amino group in the compound of formula (VI) may be
methylated with methylating agents such as Mel and
Me.sub.2SO.sub.4, wherein Me is methyl. The methylation is carried
out using conventional procedures for carrying out such
reactions.
[0058] Alternatively, citalopram is formed by reductive amination.
According to this procedure, the compound of formula (VI) is
reacted with compounds such as formaldehyde, paraformaldehyde or
trioxan in presence of a reducing agent such as NaBH.sub.4 or
NaBH.sub.3CN. The reductive amination is carried out using
conventional procedures for carrying out such reactions.
[0059] The compound of formula (VIIa) or (VIIb) may suitably be
converted to the corresponding aldehyde by treatment with an
organic or mineral acid or with resins carrying H.sup.+ groups such
as Dowex H.sup.+ or Amberlyst.
[0060] The resulting aldehyde may be converted to citalopram by
reductive amination, i.e. by reaction with dimethylamine in the
presence of a reducing agent such as NaBH.sub.4 or NaBH.sub.3CN.
Dimethylamine may be added to the reaction in the form of the
dimethylammonium chloride salt.
[0061] The ester derivative of formula (VIII) may be converted to
citalopram via the corresponding alcohol of formula (IV) by
reduction of the ester using Red-Al as a reducing agent or via the
corresponding amide of formula (V) by reaction of the ester with
NH(Me).sub.2 or a metal salt thereof.
[0062] Suitable, the agent useful for conversion of a compound of
formula (IX) to a compound of formula (VI) is NaOH/Br.sub.2.
[0063] Oxidation of the compound of formula (X) may be carried out
by treatment of the compound with ozone in a polar solvent such as
alcohol, water, acetic acid or esters thereof. Alternatively, the
compound of formula (X) may be treated with oxidation agents such
as NaIO.sub.4, OsO.sub.4/NaIO.sub.4 and KMnO.sub.4.
[0064] The reductive amination of a compound of formula (XI) may
suitably be carried out by reaction with dimethylamin in presence
of a reducing agent such as NaBH.sub.4 or NaBH.sub.3CN.
Dimethylamine may be added to the reaction in the form of
dimethylammonium chloride.
[0065] The amino group in the compounds of formula (XII) and (XIV)
may be methylated with methylating agents such as MeI and
Me.sub.2SO.sub.4, wherein Me is methyl. The methylation is carried
out using conventional procedures for carrying out such
reactions.
[0066] Alternatively, the amino group in the compounds of formula
(XII) and (XIV) may be methylated by reductive amination. According
to this procedure, the compound of formula (XII) or (XIV) is
reacted with compounds such as formaldehyde, paraformaldehyde or
trioxan in presence of a reducing agent such as NaBH.sub.4 or
NaBH.sub.3CN. The reductive amination is carried out using
conventional procedures for carrying out such reactions.
[0067] The reaction conditions, solvents, etc. used for the
reactions described above are conventional conditions for such
reactions and may easily be determined by a person skilled in the
art.
[0068] The starting material of formula (I) may be prepared as
described in U.S. Pat. No. 4,136,193 or as described in WO
98/019511.
[0069] The compounds of formula (II) are commercially available or
may be prepared from commercially available starting materials
using conventional techniques.
[0070] Citalopram is on the market as an antidepressant drug in the
form of the racemate. However, in the near future the active
S-enantiomer of citalopram is also going to be introduced to the
market.
[0071] S-citalopram may be prepared by separation of the optically
active isomers by chromatography.
[0072] Throughout the specification and claims, the term alkyl
refers to a branched or unbranched alkyl group having from one to
six carbon atoms inclusive, such as methyl, ethyl, 1-propyl,
2-propyl, 1-butyl, 2-butyl, 2-methyl-2-propyl, 2,2-dimethyllethyl
and 2- methyl-1-propyl.
[0073] Similarly, alkenyl and alkynyl, respectively, designate such
groups having from two to six carbon atoms, including one double
bond or triple bond respectively, such as ethenyl, propenyl,
butenyl, ethynyl, propynyl and butynyl.
[0074] The term aryl refers to a mono or bicyclic carbocyclic
aromatic group, such as phenyl and naphthyl, in particular
phenyl.
[0075] The term aralkyl refers to arylalkyl, wherein aryl and alkyl
is as defined above.
[0076] Optionally alkyl substituted aryl and aralkyl refers to aryl
and aralkyl groups which may optionally be substituted with one or
more alkyl groups.
[0077] Halogen means chloro, bromo or iodo.
[0078] Citalopram may be used as the free base, in particular the
free base in crystalline form, or as a pharmaceutically acceptable
acid addition salt thereof. As acid addition salts, such salts
formed with organic or inorganic acids may be used. Exemplary of
such organic salts are those with maleic, fumaric, benzoic,
ascorbic, succinic, oxalic, bismethylenesalicylic, methanesulfonic,
ethanedisulfonic, acetic, propionic, tartaric, salicylic, citric,
gluconic, lactic, malic, mandelic, cinnamic, citraconic, aspartic,
stearic, palmitic, itaconic, glycolic, paminobenzoic, glutamic,
benzene sulfonic and theophylline acetic acids, as well as the
8halotheophyllines, for example 8bromotheophylline. Exemplary of
such inorganic salts are those with hydrochloric, hydrobromic,
sulfuric, sulfamic, phosphoric and nitric acids.
[0079] The acid addition salts of the compounds may be prepared by
methods known in the art. The base is reacted with either the
calculated amount of acid in a water miscible solvent, such as
acetone or ethanol, with subsequent isolation of the salt by
concentration and cooling, or with an excess of the acid in a water
immiscible solvent, such as ethylether, ethylacetate or
dichloromethane, with the salt separating spontaneously.
[0080] The pharmaceutical compositions of the invention may be
administered in any suitable way and in any suitable form, for
example orally in the form of tablets, capsules, powders or syrups,
or parenterally in the form of usual sterile solutions for
injection.
[0081] The pharmaceutical formulations of the invention may be
prepared by conventional methods in the art. For example, tablets
may be prepared by mixing the active ingredient with ordinary
adjuvants and/or diluents and subsequently compressing the mixture
in a conventional tabletting maschine. Examples of adjuvants or
diluents comprise: Corn starch, potato starch, talcum, magnesium
stearate, gelatine, lactose, gums, and the like. Any other adjuvant
or additive, colourings, aroma, preservatives etc. may be used
provided that they are compatible with the active ingredients.
[0082] Solutions for injections may be prepared by solving the
active ingredient and possible additives in a part of the solvent
for injection, preferably sterile water, adjusting the solution to
the desired volume, sterilising the solution and filling it in
suitable ampoules or vials. Any suitable additive conventionally
used in the art may be added, such as tonicity agents,
preservatives, antioxidants, etc.
[0083] The invention is further illustrated by the following
examples.
EXAMPLE 1
[0084] A solution of
1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carboni- trile (4.8
g, 0.02 mol) in THF (50 mL) was added dropwise to a solution of LDA
(Butyl lithium 1.6 M (15 mL), disopropylamine 2.6 g) at -30.degree.
C. under an atmosphere of nitrogen. After stirring at -30 C. for 10
minutes a solution of the alkyl halide (0.02 mol) in THF (25 mL)
was added dropwise and allowed to warm to room temperature and
stirred for a further 60 minutes. The reaction was then quenched
with ice, extracted with toluene (3.times.50 mL), washed with water
(50 mL) and concentrated under reduced pressure. The residue was
purified by chromatography on silica gel using mixtures of
n-heptane/EtOAc as the eluent. The resulting anion is then reacted
with a compound of formula (II).
EXAMPLE 2
[0085] Preparation of
1-[(3-benzyloxy)propyl]-1-(4-fluorophenyl)-1,3-dihyd-
ro-5-isobenzofurancarbonitrile:
[0086] A solution of
1-(4fluorophenyl)-1,3-dihydro-5-isobenzofurancarbonit- rile (2.2 g,
9.2 mmol) in THF (40 mL) was added to a solution of LDA (12 mmol)
in THF (70 mL) at -78.degree. C. under an atmosphere of nitrogen.
After stirring at -78.degree. C. for 30 min, a solution of
benzyl-3-bromopropylether (2 mL., 12 mmol) in THF (10 mL) was added
and the resulting mixture was allowed to warm to room temperature
and stirred for 2 h. Then the mixture was poured into ice/H.sub.2O
(100 mL) and extracted with Et.sub.2O (3.times.150 mL). The organic
extracts were washed with H.sub.2O (100 mL) and brine (100 mL),
dried and evaporated. Silica gel chromatography (heptane, EtOAc
5:1) of the residue gave the product as an oil (2.0 g, 60%).
.sup.1H NMR (DMSOd.sub.6) .delta.1.35 (1H, m); 1.45 (1H, m); 2.23
(2H, m); 3.38 (2H, dd, J=5.5 and 6.6 Hz)); 4.38 (2H, s); 5.14 (1H,
d, J=13.7 Hz); 5.19 (1H, d, J=13.7 Hz); 7.15 (2H, t, J=8.8 Hz);
7.25 (3H, J=7.27 Hz); 7.32 (2H, m); 7.58 (2H, dd, J=5.6 and 8.8
Hz); 7.75 (3H, m).
[0087] Preparation of
1-(4-fluorophenyl)-1-[3-(tetrahydropyranyloxy)propyl-
]-1,3-dihydro-5-isobenzo-furancarbonitrile:
[0088] The same procedure was used to give the title compound as an
oil (2.0 g, 60%). .sup.1H NMR (DMSO-d.sub.6).delta.1.40 (6H, m);
1.52 (1H, m); 1.65 (1H, m); 2.20 (2H, m); 3.30 (1H, m); 3.38 (1H,
m); 3.55 (1H, m); 3.65 (1H, m); 4.45 (1H, dd); 5.15 (1H, d, J=13.0
Hz); 5.19 (1H, d, J=13.0 Hz); 7.15 (2H, t, J =8.8 Hz); 7.58 (2H,
dd, J=5.7 and 9.0 Hz); 7.75 (1H, d, J=8.0 Hz); 7.79 (2H, s+d, J=8.0
Hz).
EXAMPLE 3
[0089] Preparation of
1-(4-fluorophenyl)-1-(3-hydroxypropyl)-1,3-dihydro-5-
-isobenzofurancarbonitrile:
[0090] (i) A solution of
1-(4-fluorophenyl)-1,3-dihydro-5-isobenzofurancar- bonitrile (13.4
g, 60 mmol) in THF (450 mL) was added to a solution of LDA (76
mmol) in THF (30 mL) at 78.degree. C. under an atmosphere of
nitrogen. After stirring at 78.degree. C. for 30 min, a solution of
(3-bromopropoxy)-tert-butyldimethylsilane (16.8 mL, 72 mmol) in THF
(30 mL) was added and the resulting mixture was allowed to warm to
room temperature and stirred for 2 h. Then the mixture was poured
into ice/H.sub.2O (400 mL), and extracted with Et.sub.2O
(3.times.500 mL). The organic extracts were washed with H.sub.2O
(500 mL) and brine (500 mL), dried and evaporated. The residue was
dissolved in methanol (400 mL) and was added 1 M HCI (200 mL). The
resulting solution was stirred at room temperature for 1 h and
evaporated. Silica gel chromatography (heptane, EtOAc 5:1) of the
residue gave the title product as an oil (14.4 g, 81%). .sup.1H NMR
(DMSOd.sub.6) .delta.1.25 (2H, m); 2.18 (2H, t, J=8.8 Hz); 3.31
(2H, q, J=6.2 Hz); 4.34 (1H, t, J=6.2 Hz); 5.12 (1H, d, J=13.2 Hz);
5.17 (1H, d, J=13.2 Hz); 7.15 (2H, t, J=8.8 Hz); 7.58 (2H, dd,
J=6.0 and 8.8 Hz); 7.72 (1H, s); 7.78 (2H, br d, J=6.0 Hz.).
.sup.13C NMR (DMSOd--.sub.6) .delta.27.4; 37.3; 59.8; 71.0; 90.7;
110.5; 114.8; 115.2; 118.8; 123.2; 125.6; 126.9; 127.1; 132.0;
139.9; 140.6; 149.5; 160.9; 162.0.
[0091] (ii) To a solution of
1[(3-benzyloxy)propyl]-1-(4-fluorophenyl)-1,3-
-dihydro-5-isobenzofurancarbonitrile (1.2 g, 3.1 mmol) and
1,4-cyclohexadiene (5.5 mL, 58.1 mmol) in ethanol (50 mL) was added
Pd/C (4 g, 5%). The reaction mixture was refluxed under a nitrogen
atmosphere for 2 days, then cooled to room temperature and filtered
through Celite. The filtrate was evaporated and the residue was
purified by silica gel chromatography to give the title product as
an oil (0.75 g, 80%). .sup.1H NMR (CDCl.sub.3).delta.1.5 (2H, m);
2.25 (2H, m); 3.5 (2H, t); 5.2 (2H, dd); 7.05 (2H, t, J=10.0 Hz);
7.41 (3H, m); 7.49 (1H, br s); 7.56 (2H, J=7.0 Hz).
[0092] (iii) To a solution of
1-(-4-fluorophenyl)-1-[3(tetrahydropyranylox-
y)propyl]-1,3-dihydro-5-isobenzofurancarbonitrile (1.5 g, 4.1 mmol)
in methanol was added catalytic amount of p-toluenesulfonic acid
monohydrate (60 mg) and the resulting mixture was stirred at room
temperature for 1 h and then evaporated. Silica gel chromatography
(heptane, EtOAc 5:1) gave the title product (1.0 g, 91%). .sup.1H
NMR (CDCl.sub.3) was identical with that obtained from
1-[(3-benzyloxy)propyl]-1-(4-fluorophenyl)-1,3-di-
hydro-5-isobenzofurancarbonitrile.
EXAMPLE 4
[0093] Preparation of
1-(4-fluorophenyl)-1-[(3-p-toluenesulfonyloxy)propyl-
]-1,3-dihydro-5-isobenzofurancarbonitrile:
[0094] To a solution of
1-(4-fluorophenyl)1-(3-hydroxypropyl)-1,3-dihydro--
5-isobenzofurancarbonitrile (2.5 g, 8.4 mmol) in toluene (50 mL) at
0-5.degree. C. were added triethylamine (2.5 mL, 18.0 mmol) and a
solution of p-toluenesulfonyl chloride (2.6 g, 13.6 mmol) in
toluene (10 mL). The resulting mixture was stirred at room
temperature for 3 days, then washed with H.sub.20 and saturated
aqueous NaHCO.sub.3 solution. Evaporation of the organic extract
followed by silica gel chromatography (heptane, EtOAc 4:1) of the
residue gave the title product as an oil (1.6 g, 42%). .sup.1H NMR
(CDCl.sub.3) .delta.1.6 (2H, m); 2.15 (2H, m); 2.45 (3H, s); 4.05
(2H, t, J=8.0 Hz); 5.15 (2H, s); 7.05 (2H, t, J=8.5 Hz); 7.30-7.42
(5H, m); 7.50 (1H, s); 7.6 (1H, d, J=7.5Hz); 7.75 (2H, d, J=7.5
Hz).
EXAMPLE 5
[0095] Preparation of
1-(4-fluorophenyl)-1-[(3-methanesulfonyloxy)propyl]--
1,3-dihydro-5-isobenzo furancarbonitrile:
[0096] To a solution of
1-(4-fluorophenyl)-1-(3-hydroxypropyl)-1,3-dihydro-
-5-isobenzofurancarbonitrile (14.4 g, 50.0 mmol) in THF (500 mL) at
0-5.degree. C. were added triethylamine (30 mL, 41.8 mmol) and a
solution of methanesulfonyl chloride (11.6 mL, 150 mmol) in THF (20
mL). The resulting mixture was stirred at room temperature
overnight, then added toluene (200 mL) and washed with H.sub.2O and
saturated aqueous NaHCO.sub.3 solution. Evaporation of the organic
phase followed by silica gel chromatography (heptane, EtOAc 3:1) of
the residue gave the title product as an oil (12.0 g, 64%). .sup.1H
NMR (CDCl.sub.3) .delta.1.70 (2H, m); 2.25 (2H, m); 2.90 (3H, s);
4.22 (2H, t, J=7.0 Hz); 5.14 (IH, d, J=13.2 Hz); 5.14 (1H, d,
J=13.2 Hz); 7.01 (2H,t, J=9.0 Hz); 7.41 (2H, d; J =9.0 Hz); 7.45
(1H, d,J=8.0 Hz); 7.52(1H, s); 7.61 (1H,br d,J=8.0 Hz).
EXAMPLE 6
[0097] Preparation of
1-[3-(N,N-dimethylamino)propyl]-1-(4-fluorophenyl)-1-
,3-dihydro-5-isobenzofurancarbonitrile, (Citalopram, Oxalate):
[0098] To a solution of
1-(4-fluorophenyl)-1-[(3-p-toluenesulfonyloxy)prop-
yl]-1,3-dihydro-5-isobenzofurancarbonitrile (0.20 g, 0.4 mmol) in
DMF (10 mL) was added triethylamine (1.4 mL, 7.0 mmol) and
dimethylammonium chloride (0.41 g, 5.0 mmol). The reaction mixture
was stirred at 70.degree. C. overnight, then cooled to room
temperature, poured into ice/H.sub.2O and extracted with Et.sub.2O
(3.times.30 mL). The organic extracts were washed with H.sub.2O and
brine, and evaporated. The residue was purified by silica gel
chromatography (heptane, EtOAc, triethylamine 1:3:4%) and
crystallised from acetone as the oxalate salt (0.12 g, 70%). DSC
(open chamber), T.sub.onset=158.96, T.sub.peak=162.14. .sup.1H NMR
(DMSO-d.sub.6) .delta.1.42 (1H, m); 1.51 (1H, m); 2.22 (2H, t,
J=8.0 Hz); 2.62 (6H, s); 2.95 (2H, t, J =8.0 Hz); 5.15 (1H, d,
J=14.0 Hz); 5.23 (1H, d, J=14.0 Hz); 7.18 (2H, t, J=9.0 Hz); 7.59
(2H, dd, J=5.0 and 8.0 Hz); 7.74 (1H, d, J=7.5 Hz); 7.79 (1H, d,
J=7.0 Hz); 7.80 (1H, br s). .sup.13C NMR (DMSO-d.sub.6).delta.19.3;
37.0; 42.3; 56.7; 71.2; 90.3; 110.7; 115.2; 115.3; 118.8; 123.2;
125.8; 127.0; 132.1; 139.9; 140.0; 148.161.4; 164.3. Anal.
(C.sub.20H.sub.21N.sub.2O, C.sub.2H.sub.2O.sub.4) calcd. C: 63.76;
H:5.59; N:6.76. Found C:63.50; H:5.78; N:6.63.
EXAMPLE 7
[0099] Preparation of
1-[3-(N,N-dimethylamino)propyl]-1-(4-fluorophenyl)-1-
,3-dihydro-5-isobenzofurancarbonitrile, (Citalopram, Oxalate):
[0100] Dimethylamine (18 mL, 100 mmol, 33% in ethanol) was added to
a solution of
1-(4-fluorophenyl)-1-[(3-methanesulfonyloxy)propyl]-1,3-dihyd-
ro-5-isobenzofurancarbonitrile (1.0 g, 2.7 mmol) in ethanol (10 mL)
and THF (20 mL). The resulting mixture was stirred at room
temperature for 1 h and at 60.degree. C. for 3 h. After cooling,
the reaction mixture was evaporated. 1 M NaOH (70 mL) was added to
the residue and extracted with Et.sub.2O (100 mL). The organic
extract was washed with brine, dried and evaporated. The residue
was filtered through silica gel (EtOAc, heptane, triethylamine
75:25:1) and crystallised from acetone as the oxalate salt (0.72 g,
65%). DSC (open chamber), T.sub.onset=158.56, T.sub.peak=161.59.
The NMR-spectra were identical with those obtained from citalopram.
oxalate prepared in example 6. Anal. (C.sub.20H.sub.2N.sub.2O,
C.sub.2H.sub.2O.sub.4) calcd. C: 63.76; H: 5.59; N: 6.76. Found C:
63.57; H: 5.51; N: 6.77.
EXAMPLE 8
[0101] Preparation of 1-(4-fluorophenyl)-1-[3
-(phthalimidopropyl)]-1,3-di-
hydro-5-isobenzofurancarbonitrile:
[0102] A solution of
1-(4-fluorophenyl)-1,3-dihydro-5-isobenzofurancarboni- trile (4.4
g. 20 mmol) in THF (40 mL) was added to a solution of LDA (24 mmol)
in THF (70 mL) at -78.degree. C. under an atmosphere of nitrogen.
After stirring at -78.degree. C. for 30 min. a solution of
2-(3-brompropyl)phthalimide (6.4 g. 24 mmol) in THF (20 mL) was
added and the resulting mixture was allowed to warm to room
temperature and stirred for 5 h. Then the mixture was poured into
ice/H.sub.2O (200 mL), and extracted with Et.sub.2O (3.times.250
mL). The organic extracts were washed with H.sub.2O (100 mL) and
brine (100 ml) dried and evaporated. Silica gel chromatography
(heptane, EtOAc 5:1) of the residue gave the product as a yellow
powder (3.0 g, 36%). A sample was recrystallised from ethanol.
.sup.1H NMR (CDCl.sub.3).delta.1.69 (1H. m); 1.74 (1H, m): 1.93
(1H. m); 3.08 (1H, dt, J=4.7 and 12.2 Hz); 3.85 (1H, ddd, J=1.4 and
7.1 and 11.8 Hz): 4.08 (1H, ddd, J=4.2 and 10.8 and 17.9 Hz); 5.09
(1H d, J=13.1 Hz): 5.20 (1H, d, J=13.1); 6.60 (1H, d, J=7.5 Hz);
7.06 (2H, t, J=9.4 Hz): 7.28 (1H, t, J=7.5 Hz): 7.42 (1H, t, J=7.5
Hz); 7.43 (1H, s); 7.58 (1H, d, J=8.0 Hz): 7.77 (1H, d, J=7.5 Hz);
7.80 (1H, t, J=5.2 Hz); 7.95 (1H d, J=8.0 Hz). .sup.13C NMR
(CDCl.sub.3) .delta.23.4: 31.8: 59.3; 72.6: 92.3: 112.6; 114.7;
118.2; 122.9; 123.7; 124.8; 125.2; 129.0; 131.1: 131.6; 132.9;
135.8; 140.9; 144.1: 145.6: 161.6; 163.6; 170.9. Anal.
(C.sub.26H.sub.19FN.sub.2O.sub.3, 1/2 C.sub.2H.sub.5OH) calcd. C:
72.15; 11: 4.93: N: 6.23. Found C: 72.66; H: 5.14; N: 6.09.
EXAMPLE 9
[0103] Preparation of
1-(3-Azidopropyl)-1-(4-fluorophenyl)-1,3-dihydro-5-i-
sobenzofurancarbonitrile:
[0104] Sodium azide (5.5 g. 80.5 mmol) was added to a solution of
1-(4-fluorophenyl)-1-[(3-methanesulfonyloxy)propyl]-1,3dihydro-5-isobenzo-
furancarbonitrile (4.0 g. 10.6 mmol) in DMF (100 mL). The resulting
mixture was stirred at 40.degree. C. for 3 h. and then refluxed for
2 h. After cooling the reaction mixture was poured into H.sub.2O
and extracted with Et.sub.2O (4.times.200 mL). The organic extracts
were washed with H.sub.2O and brine, dried and evaporated to give
the crude product as a brown oil (1.3 g, 45%). .sup.1H NMR
(DMSO-d.sub.6).delta.1.40 (2H, m); 2.22 (2H, m); 3.30 (2H, t, J=6.6
Hz); 5.10 (1H, d, J=13.7 Hz); 5.21 (1H, d, J=13.7 Hz); 7.18 (2H, t,
J=8.5 Hz): 7.59 (2H, dd, J=5.2 and 8.5 Hz); 7.78 (3H, s+d,J=8.1
Hz).
[0105] Preparation of
1-(3-Aminopropyl)-1-(4-fluorophenl)-1,3-dihydro-5-is-
obenzofurancarbonitrile:
[0106] A mixture of
1-(3-azidopropyl)-1-(4-fluorophenyl)-1,3-dihydro-5-iso-
benzofuranearbo-nitrile (1.3 g, 4.4 mmol) and palladium on carbon
(0.6 g, 5%) in ethanol (50 mL) was hydrogenated for 2 h. The
mixture was filtered through Celite and evaporated to give the
crude product as a brown oil (0.8 g, 66%). .sup.1H NMR
(DMSO-d.sub.6).delta.1.11 (1H, m); 1.22 (1H, m); 2.12 (2H, m); 2.48
(2H, t, J=7.1 Hz); 5.15 (1H, d, J=13.7 Hz); 5.19 (1H, d, J=13.7
Hz); 7.15(2H, t, J=8.9 Hz); 7.58 (2H, dd, J=5.2 and 8.5 Hz); 7.72
(1H, d, J=8.4 Hz); 7.78 (2H, s+d, J=8.1 Hz).
[0107] Preparation of
1-[3-(N,N-Dimethyliamino)propyl]-1-(4-fluoroplenyl)--
1,3-dihydro-5-isobenzofurancarbonitrile, (Citalopram, Oxalate):
[0108] Sodium cyanoborohydride (0.34 g 5.4 mmnol) was added to a
mixture of 1 (3Aininopropyl)1(4-fluorophenyl)
-1,3-dihydro5isobenzofurancarbonitr- ile (0.80 g 2.7 mmol) and
formaldehyde (0.44 mL. 5.4 mmol, 37% in H20) in methanol (10 mL).
The resulting mixture was stirred at room temperature for 3 h. then
was added more sodium cyanoborohydride (0.17 g, 2.7 mmol) and
formaldehyde (0.22 mL, 2.7 mmol). After stirring at room
temperature for 1, the mixture was quenched with H.sub.2O and
extracted with Et.sub.2O. The organic extracts were dried and
evaporated. Silica gel chromatography (EtOAc, heptane,
triethylamine 75:25:1) of the residue gave the crude product, which
was isolated as the oxalate salt from acetone (0.31 g 0.8 mmol, 30
%). The NMR-spectra were identical with those obtained from
citalopram oxalate prepared in example 6. Anal.
(C.sub.20H.sub.21N.sub.2O, C.sub.2H.sub.2O.sub.4, {fraction
(1/4)}H.sub.2O ) calcd. C: 63.06; H: 5.67; N: 6.69. Found C: 63.28;
H: 5.64; N: 6.67.
Example 10
[0109] Preparation of
1-(4-fluorophenyl)-1-[3-(N-methylamino)propyl]-1,3-d-
ihydro-5-isobenzofurancarbonitrile, Oxalate Salt:
[0110] The compound was prepared from methylamine (60 mL, 120 mmol,
2 M solution in THF) using the method described in example 7.
Yield: 760 mg, 36%. .sup.1H NMR (DMSO-d.sub.6) .delta.1.40 (1H, m);
1.41 (1H, m); 2.25 (2H, t); 2.47 (31H, s); 2.83 (2H, t, J=8.0 Hz);
5.15 (1H, d, J=13.2 Hz); 5.21 (1H, d, J=13.2 Hz); 7.18 (2H, t,
J=9.0 Hz); 7.59 (2H, dd, J=5.6 and 7.5 Hz); 7.73 (1H, d, J=8.1 Hz);
7.81 (3H, d+s, J=8.1 Hz).
[0111] Preparation
1-[3-(N,N-Dimethylamino)propyl]-1-(4-fluorophenyl)-1,3--
dihydro-5-isobenzofurancarbonitrile, (Citalopram, Oxalate):
[0112] A solution of
1-[3-(N-methyl-ammonium)propyl]-1-(4-fluorophenyl)-1,-
3-dihydro-5-isobenzofurancarbonitrile (0.70 g, 2.24 mmol) and
formaldehyde (0.5 mL, 6.7 mmol, 37% aqueous solution) in 98% formic
acid (5 mL) was refluxed for 4 h. After cooling, 4 M HCI (2 mL) was
added and the resulting mixture was evaporated. 1 M NaOH (50 mL)
was added to the residue and extracted with Et.sub.2O (3.times.100
mL). The organic extract was washed with brine, dried and
evaporated. The oxalate salt was isolated from acetone (0.22 g,
30%). DSC (open chamber), T.sub.onset=157.73, T.sub.peak=160.80.
The NMR-spectra were identical with those obtained from citalopram
oxalate prepared in example 6. Anal. (C.sub.20H.sub.21N.sub.2O,
C.sub.2H.sub.2O.sub.4, 1/4 H.sub.2O) calcd. C: 63.06: H: 5.67: N:
6.69. Found C: 63.24; H: 5.65; N: 6.62.
EXAMPLE 11
[0113] Preparation of
1-[3-([1,3]dioxolan-2-yl)ethyl)-1-(4-fluorophenyl)-1-
,3-dihydro-5-isobenzofurancarbonitrile:
[0114] A solution of
1-(4-fluorophenyl)-1,3-dihydro-5-isobenzofurancarboni- trile (4.46
g, 18.7 mmol) in THF (40 mL) was added to a solution of LDA (24
mmol) in THF (100 mL) at -78.degree. C. under an atmosphere of
nitrogen. After stirring at -78.degree. C. for 30 min, a solution
of 2-2-(2-bromoethyl)-[1,3]-dioxolane (2.8 mL, 24 mmol) in THF (20
mL) was added and the resulting mixture was allowed to warm to room
temperature and stirred for 2 h. Then the mixture was poured into
ice/H.sub.2O (100 mL), and extracted with Et.sub.2O (3.times.300
mL). The organic extracts were washed with H.sub.2O (100 mL) and
brine (100 mL), dried and evaporated. Silica gel chromatography
(heptane, EtOAc 5:1) of the residue gave the product as an oil (5.5
g, 86%). .sup.1H NMR (CDCl.sub.3) .delta.1.52 (1H, m); 1.70 (1H,
m); 2.28 (2H, m); 3.81 (2H, m); 3.89 (2H, m); 4.85 (1H, t, J=4.0
Hz); 5.14 (1H, d, J=13.2 Hz); 5.19 (1H, d, J=13.2 Hz); 7.04 (2H, t,
J=8.5 Hz); 7.41 (3H, m); 7.49 (1H, s); 7.58 (1H, d, J=8.0 Hz).
.sup.13C NMR (CDCl.sub.3) .delta.27.8; 34.4; 64.2; 70.6; 90.1;
103.2; 111.2; 114.5; 114.8; 117.9; 122.2; 124.5; 126.1; 126.2;
131.2; 138.7; 139.7; 148.5; 159.0.
[0115] Preparation of
1-(4-fluorophenyl)-1-(3-formylethyl)-1,3-dihydro-5-i-
sobenzofurancarbo-nitrile:
[0116] A solution of
1-[3-([1,3]dioxolan-2-yl)ethyl)-1-(4-fluorophenyl)-1,-
3-dihydro-5-isobenzofurancarbonitrile (5.30 g, 16 mmol) in 30 %
aqueous acetic acid (200 mL) was refluxed for 5 h. The reaction
mixture was cooled and extracted with CH.sub.2Cl.sub.2(3.times.400
mL). The organic extracts were dried and evaporated to give the
crude product (5.0 g, contained about 8.0 mmol of the product as
judged by NMR and HPLC, 50%), which was used in the next step
without further purification. .sup.1H NMR (CDCl.sub.3) .delta.1.49
(1H, m); 1.61 (1H, m); 2.38 (1H, m); 2.51 (1H, m); 5.15 (2H, br s);
7.01 (2H, t, J=8.0 Hz); 7.41 (3H, dd+s, J=5.6 and 8.0 Hz); 7.51
(2H, d, J=8.0 Hz); 7.61 (2H, d, J=8.0 Hz).
[0117] Preparation of
1-[3(N,N-dimethylamino)propyl]-1-(4-fluorophenyl)-1,-
3-dihydro-5-isobenzofurancarbonitrile, (Citalopram, Oxalate):
[0118] Sodium cyanoborohydride (0.76 g, 14.4 mmol) was added to a
mixture of crude
1-(3-formylethyl)-1-(4-fluorophenyl)-1,3-dihydro-5-isobenzofuran-
carbonitrile (5.0 g, contained about 8.0 mmol of the compound as
judged by NMR and HPLC) and dimethylammonium chloride (1.17 g, 14.4
mmol) in methanol (50 mL) at 0-5.degree. C. The resulting mixture
was stirred at room temperature overnight, then added toluene (100
mL) and EtOAc (100 mL) and washed with H.sub.2O (100 mL). The
aqueous phase was extracted with Et.sub.2O (2.times.100 mL). The
combined organic extracts were dried and evaporated. Silica gel
chromatography (heptane, EtOAc, triethylamine 25:25:1) of the
residue gave the title compound, which was isolated form acetone as
the oxalate salt (2.7 g, 82%). DSC (open chamber),
T.sub.onset=159.55, T.sub.peak=163.54. The NMR-spectra were
identical with those obtained from citalopram oxalate prepared in
example 6. Anal. (C.sub.20H.sub.21N.sub.2O, C.sub.2H.sub.2O.sub.4)
calcd. C: 63.76; H: 5.59; N: 6.76. Found C: 63.65; H: 5.69; N:
6.80.
* * * * *