U.S. patent application number 14/580577 was filed with the patent office on 2015-04-23 for process for the preparation of n-monosubstituted beta-amino alcohols.
The applicant listed for this patent is Lonza AG. Invention is credited to Rudolf Fuchs, Dominique Michel.
Application Number | 20150112086 14/580577 |
Document ID | / |
Family ID | 30011063 |
Filed Date | 2015-04-23 |
United States Patent
Application |
20150112086 |
Kind Code |
A1 |
Michel; Dominique ; et
al. |
April 23, 2015 |
Process for the Preparation of N-Monosubstituted beta-Amino
Alcohols
Abstract
A process is disclosed for the preparation of a compound of
formula ##STR00001## and/or an addition salt of a proton acid,
wherein R.sup.1 and R.sup.2 independently represent alkyl,
cycloalkyl, aryl or aralkyl, each aryl or aralkyl being optionally
further substituted with alkyl, alkoxy and/or halogen.
Inventors: |
Michel; Dominique; (Sierre,
CH) ; Fuchs; Rudolf; (Sitten, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lonza AG |
Basel |
|
CH |
|
|
Family ID: |
30011063 |
Appl. No.: |
14/580577 |
Filed: |
December 23, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13950412 |
Jul 25, 2013 |
8962865 |
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14580577 |
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12868419 |
Aug 25, 2010 |
8558014 |
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13950412 |
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12801231 |
May 28, 2010 |
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12868419 |
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10520362 |
Apr 18, 2005 |
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PCT/EP2003/007411 |
Jul 9, 2003 |
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12801231 |
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12003752 |
Dec 31, 2007 |
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10520362 |
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10520362 |
Apr 18, 2005 |
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12003752 |
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Current U.S.
Class: |
549/72 ; 549/483;
549/75; 564/342 |
Current CPC
Class: |
C07C 221/00 20130101;
C07C 225/16 20130101; C07C 213/00 20130101; C07D 333/56 20130101;
C07D 307/42 20130101; C07D 333/22 20130101; C07D 307/46 20130101;
C07D 307/52 20130101; C07D 333/16 20130101; C07D 307/80 20130101;
C07D 333/20 20130101 |
Class at
Publication: |
549/72 ; 549/483;
564/342; 549/75 |
International
Class: |
C07D 333/22 20060101
C07D333/22; C07C 225/16 20060101 C07C225/16; C07D 333/20 20060101
C07D333/20; C07D 307/52 20060101 C07D307/52 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 9, 2002 |
EP |
02015229 |
Claims
1-8. (canceled)
9. A compound of formula ##STR00016## and its addition salts of
proton acids, wherein R.sup.1 represents furanyl, benzofuranyl,
isobenzofuranyl, thienyl or benzo[b]thienyl, each being optionally
substituted with halogen, linear or branched C.sub.1-4 alkyl,
linear or branched C.sub.1-4 alkoxy, C.sub.3-.sub.6 cycloalkyl,
CF.sub.3, C.sub.2F.sub.5, OCF.sub.3 or OC.sub.2F.sub.5; and wherein
R.sup.2 is selected from the group consisting of linear or branched
C.sub.1-8 alkyl, C.sub.3-8 cycloalkyl, phenyl, naphthyl, furanyl,
benzofuranyl, thienyl, benzo[b]thienyl and aralkyl, wherein the
alkyl moiety of the aralkyl residue is linear C.sub.1-4 alkyl, and
the aryl moiety is selected from the group consisting of phenyl,
naphthyl, furanyl, benzofuranyl, thienyl and benzo[b]thienyl, each
aryl or aralkyl being optionally substituted with halogen, linear
or branched C.sub.1-4 alkyl, linear or branched C.sub.1-4 alkoxy,
C.sub.3-6 cycloalkyl, CF.sub.3, C.sub.2F.sub.5 OCF.sub.3 or
OC.sub.2F.sub.5 with the exception of the compound wherein R.sup.1
represents thienyl and R.sup.2 represents benzyl.
10-11. (canceled)
12. A compound of formula ##STR00017## and its addition salts of
proton acids.
13-20. (canceled)
Description
[0001] The invention relates to a process for the preparation of
N-monosubstituted .beta.-amino alcohols of formula
##STR00002##
and/or an addition salt of a proton acid via direct synthesis of
N-monosubstituted .beta.-keto amines of formula
##STR00003##
and/or an addition salt of a proton acid.
[0002] N-Monosubstituted .beta.-amino alcohols of formula I like
(S)-(-)-3-N-methylamino-1-(2-thienyl)-1-propanol (LY293628) are
useful key intermediates and building blocks for the preparation of
pharmaceutically active compounds like
(S)-(+)-methyl-[3-(1-naphthyloxy)-3-(2-thienyl)-propyl]-amine
((S)-duloxetine) (Liu, H. et al., Chirality 12 (2000) 26-29), a
potential neuro-active compound which strongly inhibits the
serotonine and norephedrine uptake (Deeter, J. et al., Tetrahedron
Lett 31 (1990) 7101-7104).
##STR00004##
[0003] In the following the terms "amine" or "amines" include their
corresponding addition salts of proton acids.
[0004] Direct preparation of N-monosubstituted .beta.-keto amines
of formula II establishes an alternative and economically
advantageous source for industrial production of N-monosubstituted
.beta.-amino alcohols of formula I.
[0005] Compounds of formula II were first synthesized in 1922 by
reacting ketones with formaldehyde and primary or secondary
alkylamines in the presence of hydrochloric acid (Mannich, C. et
al., Chem. Ber. 55 (1922) 356-365). In said reactions with primary
alkylamines formation of hydrochlorides of tertiary .beta.-keto
amines of formula
##STR00005##
prevails over formation of hydrochlorides of secondary .beta.-keto
amines of formula II. These findings were supported by Blicke et
al. (J. Am. Chem. Soc. 64 (1942) 451-454) and Becker et al. (Wiss.
Z. Tech. Hochsch. Chem. Leuna-Merseburg. 11 (1969) 38-41).
[0006] According to Mannich et al. steam destillation of tertiary
.beta.-keto amines of formula III results in formation of secondary
.beta.-keto amines of formula II in fairly satisfactory yields,
accompanied by vinyl compounds and other by-products.
[0007] In spite of the loss of more than 50% of the starting
compounds and due to lack of alternative processes this procedure
is still used for the preparation of secondary .beta.-keto
amines.
[0008] Another drawback in presently known preparation methods of
.beta.-keto amines is the need of isolation of the desired
intermediate compounds of formula II from unwanted by-products of
formula III.
[0009] EP-A 457 559 and EP-A 650 965 disclose the preparation of
N,N-dimethyl .beta.-amino alcohols via Mannich-type reactions of
methyl ketones with paraformaldehyde and dimethylamine followed by
reduction of the carbonyl group. After reaction of the hydroxyl
group affording alkyl or aryl ether derivatives one methyl radical
is removed to obtain N-monosubstituted compounds which requires
delicate and expensive reactions.
[0010] Only Becker et al. disclose some few examples with yields of
about 60% of N-monomethyl .beta.-keto amines using N-methylammonium
oxalates as nitrogen source. Nevertheless, the process disclosed by
Becker et al. is not advantageous because it strictly depends on
the use of amino oxalates. In contrast to the free amines or
corresponding hydrochlorides oxalates of primary amines are not
commercially available and their preparation requires further
synthesis and purification steps.
[0011] Using oxalates is also disadvantageous because it requires
additional reduction equivalents in the next step, reducing the
ketone intermediates to the title compounds.
[0012] None of the known processes for the production of
N-monosubstituted .beta.-amino alcohols of formula I and ether
derivatives thereof includes, intends or concerns intermediate
products comparable to N-monosubstituted .beta.-keto amines of
formula II of the present invention. Although still many efforts
were made to find new preparation processes, the pathway of the
present invention for direct synthesis of N-monosubstituted
.beta.-keto amines and subsequent reduction to N-monosubstituted
.beta.-amino alcohols is not yet disclosed.
[0013] The problem to be solved was to provide an alternative and
efficient process for the synthesis of N-monosubstituted
.beta.-amino alcohols and derivatives thereof in high yields.
Furthermore, the proposed process should provide high yields
independently of steric aspects of the used amino or carbonyl
compounds.
[0014] The problems mentioned above could be solved according to
claim 1.
[0015] Starting with commercially available methyl ketones and
primary amines and/or an addition salt of a proton acid, which were
reacted with formaldehyde in the presence a solvent and optionally
of a proton acid at a pressure above 1.5 bar N-monosubstituted
.beta.-amino ketones which could be directly reduced to the desired
N-monosubstituted .beta.-amino alcohols were obtained in high
yields.
[0016] As a further advantage of the instant process high yields of
N-monomethyl .beta.-amino ketones can be obtained by direct usage
of methylamine hydrochloride which is easily available, cheap and,
since it is a solid compound, easy to handle.
[0017] The present invention discloses a process for the
preparation of a compound of formula
##STR00006##
and/or an addition salt of a proton acid, wherein R.sup.1 and
R.sup.2 independently represent alkyl, cycloalkyl, aryl or aralkyl,
each being optionally further substituted with alkyl, alkoxy and/or
halogen, which process comprises the steps of [0018] a) reacting a
mixture comprising [0019] (i) a methyl ketone of formula
[0019] ##STR00007## wherein R.sup.1 is as defined above, [0020]
(ii) a compound of formula
[0020] H.sub.2N--R.sup.2
and/or an addition salt of a proton acid, wherein R.sup.2 is as
defined above, and (iii) formaldehyde or a source of formaldehyde
selected from the group consisting of formaldehyde in aqueous
solution, 1,3,5-trioxane, paraformaldehyde and mixtures thereof, in
the presence of [0021] a solvent selected from the group consisting
of water, aliphatic alcohols, cycloaliphatic alcohols and mixtures
thereof, and [0022] optionally a proton acid to afford a compound
of formula
##STR00008##
[0023] and/or an addition salt of a proton acid, and [0024] b)
reducing the carbonyl group of said .beta.-amino ketone to afford a
compound of formula I, and/or an addition salt of a proton acid,
wherein the first step is carried out at a pressure above 1.5
bar.
[0025] In a preferred embodiment R.sup.1 and R.sup.2 can
independently represent linear or branched C.sub.1-8 alkyl,
C.sub.3-8 cycloalkyl, phenyl, naphthyl, furanyl, benzofuranyl,
thienyl, benzo[b]thienyl or aralkyl, wherein the alkyl moiety of
the aralkyl residue is linear C.sub.1-4 alkyl, and the aryl moiety
is selected from the group consisting of phenyl, naphthyl, furanyl,
benzofuranyl, thienyl and benzo[b]thienyl,
each aryl or aralkyl being optionally substituted with halogen,
linear or branched C.sub.1-4 alkyl, linear or branched C.sub.1-4
alkoxy, C.sub.3-6 cycloalkyl, CF.sub.3, C.sub.2F.sub.5, OCF.sub.3
or 0C.sub.2F.sub.5.
[0026] It is particularly preferred that R.sup.1 represents furanyl
or thienyl.
[0027] It is also particularly preferred that R.sup.2 represents
linear or branched C.sub.1-8 alkyl. More particularly preferred
R.sup.2 represents methyl, ethyl, propyl, isopropyl, butyl,
isobutyl or tert-butyl.
[0028] Preferably, the compound of formula V is used as a free
amine and/or an addition salt of a proton acid. Particularly
preferred are free amines, formates, acetates, oxalates,
hydrochlorides, hydrobromides or mixtures thereof. More
particularly preferred are free amines and/or hydrochlorides.
[0029] In a preferred embodiment the compound of formula V is
present in an amount at least equimolar to that of the compound of
formula IV. Particularly preferred the molar ratio of the compound
of formula V to the compound of formula IV is between 1 and 2.
[0030] In a preferred embodiment the solvent comprises water, an
aliphatic or cycloaliphatic alcohol or a mixture thereof.
[0031] Particularly preferred alcohols are linear or branched
aliphatic C.sub.1-12 alcohols, cycloaliphatic C.sub.5-8 alcohols,
di- and/or trimeric ethylene glycols or mono C.sub.1-4 alkyl or
acetyl derivatives thereof, each of said alcohols containing 1 to 3
hydroxy groups.
[0032] Examples for said alcohols are methanol, ethanol, propanol,
isopropyl alcohol, butanol, isobutanol, tert-butanol, 2-butanol,
1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol,
cyclopentanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol,
1,2-butanediol, 2,3-butanediol, 1,4-butanediol, 1,2,3-propanetriol,
1,2,6-hexanetriol, diethylene glycol, diethylene glycol monomethyl
ether, diethylene glycol monoethyl ether, diethylene glycol
monobutyl ether, diethylene glycol monoacetate, triethylene glycol,
triethylene glycol monomethyl ether, triethylene glycol monoethyl
ether, triethylene glycol monobutyl ether and triethylene glycol
monoacetate.
[0033] Preferably said alcohol is ethanol, propanol, isopropyl
alcohol, butanol, isobutanol, tert-butanol, diethylene glycol or
triethylene glycol.
[0034] The proton acid can be any organic or inorganic acid, the
acid being preferably selected from the group consisting of formic
acid, acetic acid, propionic acid, oxalic acid, malonic acid,
benzoic acid, HF, HCl, HBr, HI, H.sub.2SO.sub.4 and
H.sub.3PO.sub.4. In a preferred embodiment the proton acid can be
an acidic salt of a polybasic organic or inorganic acid like
monoalkali malonates, alkali hydrogensulfates, alkali
hydrogenphosphates and alkali hydrogencarbonates.
More preferably the proton acid is selected from the group
consisting of formic acid, acetic acid, propionic acid, oxalic
acid, HCl and HBr, more preferably it is selected from the group
consisting of formic acid, acetic acid, HCl and HBr.
[0035] Preferably reaction step a) is carried out either with added
addition salts of amines or proton acids, since even distilled free
.beta.-amino ketones of formula II tend to decompose and form
by-products while stored, whereas the corresponding additions salts
can be stored over a longer period without decomposition. In the
products, the ratio of free amine and its salt corresponds to the
ratio of added addition salts of amines and proton acids to the
whole amine amount during reaction step a).
[0036] In a preferred embodiment the pressure during reaction step
a) is above 1.5 bar, more preferably in the range of 1.5 to 10 bar
and particularly preferred in the range of 1.5 to 5 bar.
[0037] In contrast to Becker et al. the inventive process generally
allows direct preparation of N-monosubstituted .beta.-keto amines
and addition salts of proton acids thereof. The products obtained
by the inventive process can be reduced or subsequently reacted
without further conversion into other salts.
[0038] The present invention also provides a compound of
formula
##STR00009##
and its addition salts of proton acids, wherein R.sup.1 represents
furanyl, benzofuranyl, isobenzofuranyl, thienyl or benzo[b]thienyl,
each being optionally substituted with halogen, linear or branched
C.sub.1-4 alkyl, linear or branched C.sub.1-4 alkoxy, C.sub.3-6
cycloalkyl, CF.sub.3, C.sub.2F.sub.5, OCF.sub.3 or OC.sub.2F.sub.5,
and wherein R.sup.2 is selected from the group consisting of linear
or branched C.sub.1-8 alkyl, C.sub.3-8 cycloalkyl, phenyl,
naphthyl, furanyl, benzofuranyl, thienyl, benzo[b]thienyl and
aralkyl, wherein the alkyl moiety of the aralkyl residue is linear
C.sub.1-4 alkyl, and the aryl moiety is selected from the group
consisting of phenyl, furanyl, benzofuranyl, thienyl and
benzo[b]thienyl, each aryl or aralkyl being optionally substituted
with halogen, linear or branched C.sub.1-4 alkyl, linear or
branched C.sub.1-4 alkoxy, C.sub.3-6 cycloalkyl, CF.sub.3,
C.sub.2F.sub.5, OCF.sub.3 or OC.sub.2F.sub.5, with the exception of
the compound wherein R.sup.1 is thienyl and R.sup.2 is benzyl.
[0039] The present invention also provides a compound of
formula
##STR00010##
and its addition salts of proton acids, wherein R.sup.4 represents
methyl, ethyl, isobutyl and tert-butyl.
[0040] The present invention also provides a compound of
formula
##STR00011##
and its addition salts of proton acids.
[0041] The present invention also provides a compound of
formula
##STR00012##
and its addition salts of proton acids.
[0042] The present invention also provides a process for the
preparation of a compound of formula
##STR00013##
and/or an addition salt of a proton acid, wherein R.sup.1 and
R.sup.2 independently represent alkyl, cycloalkyl, aryl or aralkyl,
each being optionally further substituted with alkyl, alkoxy and/or
halogen, which process comprises reacting a mixture comprising
[0043] (i) a methyl ketone of formula
[0043] ##STR00014## [0044] wherein R.sup.1 is as defined above, and
[0045] (ii) a compound of formula
[0045] H.sub.2N--R.sup.2 [0046] and/or an addition salt of a proton
acid, wherein R.sup.2 is as defined above, and [0047] (iii)
formaldehyde or a source of formaldehyde selected from the group
consisting of formaldehyde in aqueous solution, 1,3,5-trioxane,
paraformaldehyde and mixtures thereof, in the presence of [0048] a
solvent selected from the group consisting of water, aliphatic
alcohols, cycloaliphatic alcohols and mixtures thereof, and [0049]
optionally a proton acid to afford a compound of formula
##STR00015##
[0049] and/or an addition salt of a proton acid, wherein R.sup.1
and R.sup.2 are as defined above, and wherein the reaction is
carried out at a pressure above 1.5 bar.
[0050] In a preferred embodiment R.sup.1 and R.sup.2 independently
represent
linear or branched C.sub.1-8 alkyl, C.sub.3-8 cycloalkyl, phenyl,
naphthyl, furanyl, benzofuranyl, thienyl, benzo[b]thienyl and
aralkyl, wherein the alkyl moiety of the aralkyl residue is linear
C.sub.1-4 alkyl, and the aryl moiety is selected from the group
consisting of phenyl, naphthyl, furanyl, benzofuranyl, thienyl and
benzo[b]thienyl, each aryl or aralkyl being optionally substituted
with halogen, linear or branched C.sub.1-4 alkyl, linear or
branched C.sub.1-4 alkoxy, C.sub.3-6 cycloalkyl, CF.sub.3,
C.sub.2F.sub.5, OCF.sub.3 or OC.sub.2F.sub.5.
[0051] It is particularly preferred that R.sup.1 represents furanyl
or thienyl. It is also particularly preferred that R.sup.2
represents linear or branched C.sub.1-8 alkyl. More particularly
preferred R.sup.2 represents methyl, ethyl, propyl, isopropyl,
butyl, isobutyl or tent-butyl.
[0052] Preferably, the compound of formula V can be used as a free
amine and/or an addition salt of a proton acid thereof.
Particularly preferred are free amines, formates, acetates,
oxalates, hydrochlorides, hydrobromides or mixtures thereof. More
particularly preferred are free amines and/or hydrochlorides.
[0053] In one preferred embodiment the compound of formula V is
present in an amount at least equimolar to that of the compound of
formula IV. Particularly preferred the molar ratio of the compound
of formula V to the compound of formula IV is between 1 and 2.
[0054] In a preferred embodiment the solvent comprises water, an
aliphatic or cycloaliphatic alcohol or a mixture thereof.
[0055] Particularly preferred alcohols are linear or branched
aliphatic C.sub.1-12 alcohols, cycloaliphatic C.sub.5-8 alcohols,
di- and/or trimeric ethylene glycols or mono C.sub.1-4 alkyl or
acetyl derivatives thereof, each of said alcohols containing 1 to 3
hydroxy groups.
[0056] Examples for said alcohols are methanol, ethanol, propanol,
isopropyl alcohol, butanol, isobutanol, tert-butanol, 2-butanol,
1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol,
cyclopentanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol,
1,2-butanediol, 2,3-butanediol, 1,4-butanediol, 1,2,3-propanetriol,
1,2,6-hexanetriol, diethylene glycol, diethylene glycol monomethyl
ether, diethylene glycol monoethyl ether, diethylene glycol
monobutyl ether, diethylene glycol monoacetate, triethylene glycol,
triethylene glycol monomethyl ether, triethylene glycol monoethyl
ether, triethylene glycol monobutyl ether and triethylene glycol
monoacetate.
[0057] Preferably said alcohol is ethanol, propanol, isopropyl
alcohol, butanol, isobutanol, tert-butanol, diethylene glycol or
triethylene glycol.
[0058] The proton acid can be any organic or inorganic acid, the
acid being preferably selected from the group consisting of formic
acid, acetic acid, propionic acid, oxalic acid, malonic acid,
benzoic acid, HF, HCl, HBr, HI, H.sub.2SO.sub.4 and
H.sub.3PO.sub.4. In a preferred embodiment the proton acid is an
acidic salt of a polybasic organic or inorganic acids like
monoalkali malonates, alkali hydrogensulfates, alkali
hydrogenphosphates and alkali hydrogencarbonates. More preferably
the proton acid is selected from the group consisting of formic
acid, acetic acid, propionic acid, oxalic acid, HCl and HBr, more
preferably it is selected from the group consisting of formic acid,
acetic acid, HCl and HBr.
[0059] In a preferred embodiment the pressure during the reaction
is above 1.5 bar, more preferably in the range of 1.5 to 10 bar and
particularly preferred in the range of 1.5 to 5 bar.
[0060] The present invention is illustrated by the following
non-limiting examples.
General Procedure for Examples 1 to 8
[0061] A mixture of methyl ketone (1 equivalent (eq)), primary
alkyl amine and/or an addition salt thereof (1.1 to 1.5 eq),
formaldehyde (1.4 to 1.5 eq), a solvent, optionally in the presence
of a proton acid, is heated in an autoclave at a total pressure
above 1.5 bar for 5 to 24 hours. Afterwards, the reaction solution
is cooled to 20.degree. C. Optionally the reaction solvent can than
be removed partly or in whole and a solvent like ethyl acetate or
isopropyl alcohol can be added under vigorous stirring, if
necessary to facilitate precipitation of the product. The
suspension is cooled (0 to 20.degree. C.) and filtered after
precipitation (0.5 to 10 hours), optionally washed and dried to
afford a slightly yellow to white powder in a yield between 50 and
75%. The product can be recrystallized from isopropyl alcohol
and/or ethyl acetate if necessary. If the stability of the free
base is sufficient at ambient conditions, extracting with an
organic solvent and an aqueous base affords the free base.
General Procedure for Comparative Examples 1 to 6
[0062] A mixture of methyl ketone (1 eq), primary alkyl amine
and/or an addition salt thereof (1 to 1.5 eq), formaldehyde (1.0 to
1.5 eq), optionally in the presence of a proton acid, is heated in
refluxing solvent for 5 to 24 hours. Afterwards, the mixture is
cooled to 20.degree. C. Optionally the reaction solvent can than be
removed partly or in whole and a solvent like ethyl acetate or
isopropyl alcohol can be added under vigorous stirring, if
necessary to facilitate precipitation of the product. The
suspension is cooled (0 to 20.degree. C.) and filtered after
precipitation (0.5 to 10 hours), optionally washed and dried to
afford a slightly yellow to white powder in a yield between 30 and
45%. The product can be recrystallized from isopropyl alcohol
and/or ethyl acetate if necessary.
EXAMPLE 1
3-(Methylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (II,
R.sup.1=thiophen-2-yl, R.sup.2=methyl)
[0063] 2-Acetylthiophene (25.5 g, 200 mmol); methylamine
hydrochloride (14.9 g, 220 mmol, 1.1 eq); paraformaldehyde (8.2 g,
280 mmol, 1.4 eq); HCl conc. (1.0 g); ethanol (100 mL); 110.degree.
C. for 9 hours; ca. 2 to 2.5 bar; removing of ethanol (50 mL) in
vacuo; addition of ethyl acetate (200 mL); ca. 71% yield.
[0064] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 9.16 (2 H, s,
br), 8.07 (1 H, dd, J=5.0, 1.0), 8.01 (1 H, dd, J=3.8, 1.0), 7.29
(1 H, dd, J=5.0, 3.8), 3.49 (2 H, t), 3.20 (2 H, t), 2.56 (3 H, s).
.sup.13C-NMR .delta. (DMSO-d.sub.6, 100 MHz): 189.9, 142.7, 135.4,
133.8, 128.8, 43.1, 34.6, 32.4.
EXAMPLE 2
3-(Methylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (II,
R.sup.1=thiophen-2-yl, R.sup.2=methyl)
[0065] 2-Acetylthiophene (24.9 g, 197 mmol); methylamine
hydrochloride (14.8 g, 219 mmol, 1.1 eq); paraformaldehyde (8.3 g,
276 mmol, 1.4 eq); HCl conc. (1.1 g); isopropyl alcohol (100 mL);
110.degree. C. for 8 hours; ca. 2 to 2.5 bar; addition of isopropyl
alcohol (50 mL); ca. 65% yield.
COMPARATIVE EXAMPLE 1
3-(Methylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (II,
R.sup.1=thiophen-2-yl, R.sup.2=methyl)
[0066] 2-Acetylthiophene (7.9 g, 300 mmol); methylamine
hydrochloride (30.4 g, 450 mmol, 1.5 eq); paraformaldehyde (12.6 g,
420 mmol, 1.4 eq); HCl conc. (1.5 g); isopropyl alcohol (200 mL);
heating under reflux (82.degree. C.) for 8 hours; addition of ethyl
acetate (200 mL); ca. 43% yield.
EXAMPLE 3
3-(Ethylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (II,
R.sup.1=thiophen-2-yl, R.sup.2=ethyl)
[0067] 2-Acetylthiophene (6.3 g, 50 mmol); ethylamine hydrochloride
(6.1 g, 75 mmol, 1.5 eq); paraformaldehyde (2.1 g, 75 mmol, 1.5
eq); HCl conc. (0.3 g); ethanol (35 mL); 110.degree. C. for 9
hours; ca. 2 to 2.5 bar; removing of ethanol (25 mL) in vacuo;
addition of ethyl acetate (50 mL); ca. 73% yield.
[0068] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 9.3 (2 H, s,
br), 8.08 (1 H, dd), 8.00 (1 H, dd), 7.28 (1 H, dd), 3.51 (2 H, t),
3.20 (2 H, t), 2.96 (2 H, q), 1.23 (3 H, t).
COMPARATIVE EXAMPLE 2
3-(Ethylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (II,
R.sup.1=thiophen-2-yl, R.sup.2=ethyl)
[0069] 2-Acetylthiophene (12.6 g, 100 mmol); ethylamine
hydrochloride (12.2 g, 150 mmol, 1.5 eq); paraformaldehyde (4.1 g,
140 mmol, 1.4 eq); HCl conc. (0.5 g); ethanol (70 mL); heating
under reflux (78.degree. C.) for 6 hours; removing of ethanol (25
mL) in vacuo; addition of ethyl acetate (70 mL); ca. 31% yield.
EXAMPLE 4
3-(Isobutylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (II,
R.sup.1=thiophen-2-yl, R.sup.2=isobutyl)
[0070] 2-Acetylthiophene (6.3 g, 50 mmol); isobutylamine
hydrochloride (8.3 g, 75 mmol, 1.5 eq); paraformaldehyde (2.1 g, 75
mmol, 1.5 eq); HCl conc. (0.3 g); ethanol (35 mL); 110.degree. C.
for 9 hours; ca. 2 to 2.5 bar; removing of ethanol (35 mL) in
vacuo; addition of ethyl acetate (50 mL); ca. 56% yield.
[0071] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 9.0 (2 H, s,
br), 8.08 (1 H, dd), 7.99 (1 H, dd), 7.29 (1 H, dd), 3.55 (2 H, t),
3.22 (2 H, t), 2.78 (2 H, d), 2.03 (1 H, m), 0.96 (6 H, d).
COMPARATIVE EXAMPLE 3
3-(Isobutylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (II,
R.sup.1=thiophen-2-yl, R.sup.2=isobutyl)
[0072] 2-Acetylthiophene (12.6 g, 100 mmol); isobutylamine
hydrochloride (16.5 g, 150 mmol, 1.5 eq); paraformaldehyde (4.1 g,
140 mmol, 1.4 eq); HCl conc. (0.5 g); butanol (70 mL); heating
under reflux (108.degree. C.) for 7 hours; addition of ethyl
acetate (100 mL); ca. 40% yield.
EXAMPLE 5
3-(tert-Butylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride
(II, R.sup.1=thiophen-2-yl, R.sup.2=tert-butyl)
[0073] 2-Acetylthiophene (6.3 g, 50 mmol); tert-butylamine
hydrochloride (8.3 g, 75 mmol, 1.5 eq); paraformaldehyde (2.1 g, 75
mmol, 1.5 eq); HCl conc. (0.3 g); butanol (35 mL); 117.degree. C.
for 9 hours; ca. 2 to 2.5 bar; addition of ethyl acetate (50 mL);
ca. 52% yield.
[0074] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 9.2 (2 H, s,
br), 8.08 (1 H, dd), 7.98 (1 H, dd), 7.30 (1 H, dd), 3.54 (2 H, t),
3.19 (2 H, t), 1.34 (9 H, s).
COMPARATIVE EXAMPLE 4
3-(tent-Butylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride
(II, R.sup.1=thiophen-2-yl, R.sup.2=tert-butyl)
[0075] 2-Acetylthiophene (12.6 g, 100 mmol); tert-butylamine
hydrochloride (16.5 g, 150 mmol, 1.5 eq); paraformaldehyde (4.1 g,
140 mmol, 1.4 eq); HCl conc. (0.5 g); butanol (70 mL); heating
under reflux (108.degree. C.) for 18 hours; addition of ethyl
acetate (100 mL); ca. 37% yield.
EXAMPLE 6
3-(Methylamino)-1-(furan-2-yl)propan-1-one hydrochloride (II,
R.sup.1=furan-2-yl, R.sup.2=methyl)
[0076] 2-Acetylfuran (7.5 g, 68 mmol); methylamine hydrochloride
(6.9 g, 102 mmol, 1.5 eq); paraformaldehyde (3.1 g, 102 mmol, 1.5
eq); HCl conc. (1.15 g); ethanol (35 mL); 110.degree. C. for 8
hours; ca. 2 to 2.5 bar; removing of ethanol (30 mL) in vacuo;
addition of ethyl acetate (50 mL); ca. 64% yield.
[0077] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 9.0 (2 H, s,
br), 8.05 (1 H, m), 7.53 (1 H, m), 6.77 (1 H, m), 3.34 (2 H, t),
3.2 (2 H, m), 2.57 (3 H, s, br).
COMPARATIVE EXAMPLE 5
3-(Methylamino)-1-(furan-2-yl)propan-1-one hydrochloride (II,
R.sup.1=furan-2-yl, R.sup.2=methyl)
[0078] 2-Acetylfuran (11.0 g, 100 mmol); methylamine hydrochloride
(10.1 g, 150 mmol, 1.5 eq); paraformaldehyde (4.1 g, 140 mmol, 1.4
eq); HCl conc. (0.5 g); butanol (70 mL); heating under reflux
(108.degree. C.) for 7 hours; addition of ethyl acetate (100 mL);
ca. 44% yield.
EXAMPLE 7
3-(Methylamino)-1-phenylpropan-1-one hydrochloride (II,
R.sup.1=phenyl, R.sup.2=methyl)
[0079] 2-Acetophenone (21.0 g, 175 mmol); methylamine hydrochloride
(17.5 g, 263 mmol, 1.5 eq); paraformaldehyde (7.9 g, 263 mmol, 1.5
eq); HCl conc. (1.1 g); ethanol (130 mL); 115.degree. C. for 24
hours; ca. 2 to 2.5 bar; addition of ethyl acetate (170 mL); ca.
52% yield.
[0080] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 9.2 (2 H, s,
br), 8.0 (2 H, m), 7.7 (1 H, m), 7.6 (2 H, m), 3.55 (2 H, t), 3.21
(2 H, t), 2.59 (3 H, s).
EXAMPLE 8
3-(Methylamino)-1-(2-naphthyl)propan-1-one hydrochloride (II,
R.sup.1=2-naphthyl, R.sup.2=methyl)
[0081] 2-Acetonaphtone (8.5 g, 50 mmol); methylamine hydrochloride
(5.1 g, 75 mmol, 1.5 eq); paraformaldehyde (2.1 g, 75 mmol, 1.5
eq); HCl conc. (0.3 g); ethanol (35 mL); 117.degree. C. for 14
hours; ca. 2 to 2.5 bar; removing of ethanol (35 mL) in vacuo;
addition of ethyl acetate (50 mL); ca. 60% yield.
[0082] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 9.3 (2 H, s,
br), 8.74 (1 H, s), 8.17 (1 H, d), 8.0 (3 H, m), 7.7 (2 H, m), 3.70
(2 H, t), 3.28 (2 H, m), 2.60 (3 H, s).
COMPARATIVE EXAMPLE 6
3-(Methylamino)-1-(2-naphthyl)propan-1-one hydrochloride (II,
R.sup.1=2-naphthyl, R.sup.2=methyl)
[0083] 2-Acetonaphtone (17.0 g, 100 mmol); methylamine
hydrochloride (10.1 g, 150 mmol, 1.5 eq); paraformaldehyde (4.1 g,
140 mmol, 1.4 eq); HCl conc. (0.5 g); ethanol (70 mL); heating
under reflux (78.degree. C.) for 5 hours; removing of ethanol (30
mL) in vacuo; addition of ethyl acetate (100 mL); ca. 42%
yield.
EXAMPLE 9
3-(Methylamino)-1-(thiophen-2-yl)propan-1-ol (I,
R.sup.1=thiophen-2-yl, R.sup.2=methyl)
[0084] To a mixture of
3-(methylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (10.3
g, 50 mmol) and ethanol (35 mL) at 4.degree. C. sodium hydroxide
(4.0 g of a 50% aqueous solution) was added in about 5 minutes.
Afterwards, neat sodium borhydride (0.95 g, 25 mmol, 1.0 eq) was
added in several portions in about 30 minutes. At the end of the
addition, the suspension was stirred for 4 h at the same
temperature, then acetone (10.0 mL) was added dropwise in 5 minutes
and the mixture was stirred for 10 additional minutes. Water (20
mL) was then added. Afterwards, the mixture was concentrated about
5 times under vacuum and the residue was extracted with tert-butyl
methyl ether (2.times.20 mL). The collected organic phases were
finally concentrated under vacuum affording an orange oil which
crystallised spontaneously after a few hours. Finally, an orange
solid was obtained (7.2 g, 84% yield). This compound can then be
used without further purification.
[0085] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 7.35 (1 H, dd,
J=4.8, 1.0), 6.94 (1 H, dd, J=4.8, 3.6), 6.90 (1 H, dd, J=3.6,
1.0), 4.90 (1 H, t), 3.7 (2 H, m), 2.56 (2 H, m), 2.25 (3 H, s),
1.79 (2 H, q).
[0086] .sup.13C-NMR .delta. (DMSO-d.sub.6, 100 MHz): 150.9, 126.3,
123.7, 122.3, 67.8, 48.5, 38.7, 36.0.
EXAMPLE 10
3-(Isobutylamino)-1-(thiophen-2-yl)propan-1-ol (I,
R.sup.1=thiophen-2-yl, R.sup.2=methyl)
[0087] To a mixture of
3-(isobutylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride (4.2
g, 19.4 mmol) and ethanol (10 mL) at 4.degree. C. sodium hydroxide
(1.6 g of a 50% aqueous solution) was added in about 20 minutes.
Afterwards, neat sodium borhydride (0.37 g, 9.7 mmol, 1.0 eq) was
added in several portions in about 30 minutes. At the end of the
addition, the suspension was stirred for 4 h at the same
temperature, then acetone (10.0 mL) was added dropwise in 20
minutes and the mixture was stirred for 10 additional minutes.
Afterwards the precipitate was removed by filtration and the
mixture was concentrated under vacuum affording an orange oil. The
crude product was purified by column chromatography using a 40:10:1
(v:v:v) mixture of methylene chloride/methanol/ammonium hydroxide
(25% aqueous solution) affording 3.1 g (76% yield) of product.
[0088] .sup.1H-NMR .delta. (DMSO-d.sub.6, 400 MHz): 7.20 (1 H, dd,
J =4.8, 1.0), 6.98 (1 H, dd), 6.94 (1 H, dd, J=4.8, 3.6), 5.20 (1
H, dd), 4.98 (2 H, br), 3.02 (1 H, m), 2.93 (1 H, m), 2.43 (2H,
symm. m), 2.03 (1 H, m), 1.97 (1 H, m), 1.80 (1 H, sept), 0.95 (6
H, d).
[0089] .sup.13C-NMR .delta. (DMSO-d.sub.6, 100 MHz): 150.9, 126.3,
123.8, 122.5, 72.1, 57.8, 48.5, 37.4, 28.2, 20.8.
* * * * *