U.S. patent application number 16/169056 was filed with the patent office on 2019-08-22 for methods and intermediates for synthesizing sk1-i.
This patent application is currently assigned to Enzo Biochem, Inc.. The applicant listed for this patent is Enzo Biochem, Inc.. Invention is credited to Zaiguo Li, Praveen Pande, Natarajan Raju.
Application Number | 20190256453 16/169056 |
Document ID | / |
Family ID | 67394033 |
Filed Date | 2019-08-22 |
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United States Patent
Application |
20190256453 |
Kind Code |
A1 |
Li; Zaiguo ; et al. |
August 22, 2019 |
METHODS AND INTERMEDIATES FOR SYNTHESIZING SK1-I
Abstract
The invention provides methods for synthesizing the compound
(2R,3S,4E)-N-methyl-5-(4'-pentylphenyl)-2-aminopent-4-ene-1,3-diol,
also known as SK1-I, and intermediate compounds used in its
synthesis.
Inventors: |
Li; Zaiguo; (Little Neck,
NY) ; Raju; Natarajan; (Germantown, MD) ;
Pande; Praveen; (Holbrook, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Enzo Biochem, Inc. |
New York |
NY |
US |
|
|
Assignee: |
Enzo Biochem, Inc.
New York
NY
|
Family ID: |
67394033 |
Appl. No.: |
16/169056 |
Filed: |
October 24, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62576943 |
Oct 25, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07D 263/06 20130101;
C07C 215/28 20130101; C07B 2200/07 20130101; C07C 213/08 20130101;
C07C 269/04 20130101; C07C 269/06 20130101; C07C 269/04 20130101;
C07C 271/22 20130101; C07C 269/06 20130101; C07C 271/16 20130101;
C07C 213/08 20130101; C07C 215/28 20130101 |
International
Class: |
C07C 215/28 20060101
C07C215/28; C07C 213/08 20060101 C07C213/08; C07D 263/06 20060101
C07D263/06 |
Claims
1. A method for synthesizing the compound ##STR00017## comprising
the reaction steps of: ##STR00018## with DIBAL in the presence of
Rochelle salt, thereby obtaining ##STR00019##
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application Ser. No. 62/576,943 filed Oct. 25, 2017 which is hereby
incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of organic
synthesis of pharmaceutical compounds.
BACKGROUND OF THE INVENTION
[0003]
(2R,3S,4E)-N-methyl-5-(4'-pentylphenyl)-2-aminopent-4-ene-1,3-diol,
also known as SK1-I and BML-258 (as HCl salt), is a pharmaceutical
inhibitor of sphingosine kinase 1 initially described in Paugh et
al., Blood. 2008 Aug. 15; 112(4): 1382-1391. An existing method for
synthesizing SK1-I is disclosed in U.S. Pat. No. 8,314,151.
[0004] What is needed and provided by the present invention are
improved methods for synthesizing SK1-I and related compounds.
SUMMARY OF THE INVENTION
[0005] One embodiment of the invention provides a method for
synthesizing the compound
##STR00001##
that includes the reaction steps of:
##STR00002##
[0006] Another embodiment of the invention provides a method for
synthesizing the compound
##STR00003##
that includes the reaction step of:
##STR00004##
[0007] A further embodiment of the invention provides a method for
synthesizing
##STR00005##
that includes the steps of: (i) reacting
##STR00006##
with DIBAL in the presence of Rochelle salt, thereby obtaining
##STR00007##
In one variation of this embodiment, Rochelle salt is provided in
an aqueous solution that further includes sodium hydroxide.
[0008] Still further embodiments of the invention provide complete
multi-step syntheses of SK1-I and salts thereof from precursor
compounds.
[0009] The invention also provides corresponding embodiments in
which one or more of the C.sub.5H.sub.11 alkyl group and the
available phenyl group hydrogens are instead, independently, a
linear or branched C.sub.1-20 alkyl group or such a group having
any subrange or number of carbons therein.
[0010] Additional features, advantages, and embodiments of the
invention may be set forth or apparent from consideration of the
following detailed description, drawings if any, and claims.
Moreover, it is to be understood that both the foregoing summary of
the invention and the following detailed description are exemplary
and intended to provide further explanation without limiting the
scope of the invention as claimed.
DETAILED DESCRIPTION OF THE INVENTION
[0011] The invention provides methods and intermediate compounds
for synthesizing the compound (2R,3
S,4E)-N-methyl-5-(4'-pentylphenyl)-2-aminopent-4-ene-1,3-diol, also
known as SK1-I, and related compounds. The structure of SK1-I is
shown below.
##STR00008##
[0012] A step-wise synthesis of SK1-I according to the invention is
exemplified as follows.
N-Boc-(D)-Serine Methyl Ester:
##STR00009##
[0014] To an ice-cooled suspension of the (D)-Serine methyl ester
hydrochloride (62.24 g, 0.4 mol) in dichloromethane (600.0 mL),
triethylamine (40.4 g, 0.4 mol) was added. After the mixture was
stirred for 30 min, Boc anhydride (96.0 g, 0.44 mol) in
dichloromethane (100 mL) was added dropwise with vigorous stirring
over 30 min. The reaction mixture was stirred for 16 hours at room
temperature. Water (600 mL) was added. The organic layer was
separated. The aqueous layer was extracted with 2.times.200 mL of
dichloromethane. The combined organic layer was washed with water
(2.times.400 mL) and dried (Na.sub.2SO.sub.4). The solution was
filtered, concentrated under reduced pressure to give an oil 93.36
g (.about.100% yield), which was used directly in the next step
without further purification.
Protection of N-Boc-(D)-Serine Methyl Ester:
##STR00010##
[0016] Boc-Serine methyl ester from above (93.0 g, 0.42 mol) and
catalyst p-toluenesulfonic acid (9.3 g) were dissolved in
dichloromethane (500 mL) and 2, 2-dimethoxypropane (500 mL). The
mixture was stirred at room temperature for 20 hours with a drying
tube. Saturated sodium bicarbonate (600.0 mL) was added. The
mixture was then stirred vigorously for 30 min. The organic layer
was separated, washed with bicarbonate (2.times.400.0 mL), water
(400.0 mL), saturated NaCl (400.0 mL) and dried (Na.sub.2SO.sub.4).
The solution was filtered and concentrated under vacuum to give
87.22 g oil (84% yield for two steps), which was used directly in
the next step without further purification.
(R)-Garner Aldehyde:
##STR00011##
[0018] To a cooled solution of the ester (87.0 g, 0.336 mol) in
anhydrous toluene (690.0 mL, -78.degree. C., acetone/dry ice bath),
DIBAL in toluene (1.49 M in toluene, 392 mL, 585.0 mmol) was added
dropwise under argon in such a way that the internal temperature
did not rise above -70.degree. C. After the addition, the reaction
mixture was stirred for an additional 4 hours at -78.degree. C.
Methanol (128 mL) was added to the mixture to quench the reaction.
The mixture was poured slowly into an aqueous solution of Rochelle
salt (potassium sodium tartrate tetrahydrate; 1.2 M, 660 g/1949 mL
water) with vigorous stirring. The mixture was stirred at room
temperature until clear separation into two layers. The aqueous
layer was extracted with diethyl ether (2.times.300.0 mL). The
combined organic layer was washed with water (2.times.800 mL) and
brine (800 mL), then dried with anhydrous Na.sub.2SO.sub.4. The
solvent was evaporated under vacuum to give aldehyde as a pale
yellow oil (68.59 g, 89%), which was used without further
purification.
Addition of 4-pentylphenyl Acetylene to the Above Aldehyde:
##STR00012##
[0019] To a cooled (-20.degree. C.) solution of
4-n-pentylphenylacetylene (51.68 g, 300 mmol) in dry THF (400 mL),
n-BuLi solution (2.5 M in hexane, 120 mL, 300 mmol) was added
dropwise under argon. After 2 hours, the mixture was cooled to
-78.degree. C., followed by the addition of HMPA
(hexmethylphosphoramide, 64.5 g, 360 mmol). After the mixture was
stirred at -78.degree. C. for an additional 30 mins, methyl
(R)-(+)-3-(t-butoxycarbonyl)-2,
2-dimethyl-4-oxazolidinecarboxaldehyde (58.0 g, 248.3 mmol) in
anhydrous THF (tetrahydrofuran; 100 mL) was added dropwise
(maintaining the temperature below -60.degree. C.). The mixture was
stirred for an additional 5 hours at -78.degree. C., then quenched
by saturated ammonium chloride solution (1000 mL). The aqueous
layer was extracted with ethyl ether (3.times.400 mL). The combined
organic layer was washed with 0.5 N HCl (2.times.400 mL) and brine
(400 mL), then dried with anhydrous sodium sulfate. The solvent was
removed under vacuum to give a yellow oil (104.04 g, .about.100%
yield), which was used without further purification.
Deprotection of the Above Oxazolidine:
##STR00013##
[0021] To an ice cooled solution of Boc-oxazolidine (103.0 g, 257.0
mmol) in methanol (1000 mL), was added conc. HCl (43.5 mL,
pre-cooled to 0.degree. C.). The mixture was stirred at room
temperature overnight and then extracted with hexane (3.times.400
mL). The pH of the methanol solution was adjusted with solid sodium
bicarbonate to 8.0. Boc anhydride (53.94 g, 245.92 mmol) was added
and the mixture was stirred at room temperature for 1-4 hours until
the disappearance of formed intermediate free amine. The solvent
was removed under vacuum. The residue was redissolved in water (300
mL) and diethyl ether (300 mL). The ethyl ether layer was dried
with anhydrous sodium sulfate and then evaporated to give a brown
oil (87.54 g, 94%), which was used without further
purification.
Reduction of the Above Alcohol:
##STR00014##
[0023] To an ice-cooled solution of the above acetylene (87.0 g,
241.0 mmol) in THF (800 mL), Red-Al (Sodium
bis(2-methoxyethoxy)aluminum dihydride; 60% w/w in toluene, 392 mL;
1.205 mol) was added dropwise over 1 hour under argon with
stirring. The solution was then stirred at room temperature for 36
hours. The reaction mixture was cooled in an ice bath and then
poured carefully into a pre-cooled solution of Rochelle salt in
water (700 g in 2200 mL of water). The mixture was vigorously
stirred until two layers were visible and well separated. The
aqueous layer was extracted with 2.times.600 mL of toluene. The
combined toluene layer was washed with water (2.times.800 mL) and
saturated sodium chloride (800 mL) and dried (Na.sub.2SO.sub.4).
The solvent was removed under vacuum to give a yellowish semi
solid, which was recrystallized with hexane (200 mL) to give a
white solid 43.3 g (purity: >98%; yield: 49%)
Deprotection to SK1-I (BML-258):
##STR00015##
[0025] To a solution of Boc protected amine (15 g, 41.3 mmol) in
anhydrous THF (300 mL), DIBAL (25% w/w in toluene, 1.49 M, 278 mL,
413 mmol) was added at room temperature under argon. The mixture
was refluxed until the starting material disappeared. The mixture
was cooled to room temperature and poured into Rochelle salt (340
g/1000 mL water) containing sodium hydroxide (50 g, .about.5%). The
mixture was stirred vigorously for 1 hour. The aqueous layer was
extracted with ethyl acetate (2.times.500 mL). The combined organic
layer was washed with water (1000 mL) and brine (1000 mL) and dried
with anhydrous sodium sulfate. The solvent was removed under vacuum
to afford yellowish oil, which turned into a pale solid after
storing at -20.degree. C. overnight. To a cold solution (ice bath)
of this solid in ethyl ether (400 mL), was added 1M HCl in ethyl
ether (50 mL). The white precipitate was collected by filtration
and washed with ethyl ether (2.times.50 mL), and then dried under
vacuum to give product as a white solid (8.11 g, 63% yield).
[0026] Advantageous improvements obtained in this synthesis of
SK1-I include the following. First, introducing HMPA in the
coupling of Garner aldehyde with acetylene improves the ratio of
the desired erythro isomer (versus undesired threo-isomer) to
.about.20:1 (from .about.8:1 without HMPA), thus eliminating the
prior necessity of column purification to remove undesired isomer
(threo-). Second, introducing Rochelle salt during the work up at
the DIBAL reduction of Boc to a methyl group (last step) increased
the yield of the pure product. And third, through a few
modifications in different steps, the prior necessity for flash
column purification was eliminated.
[0027] It should be understood that the synthesis described herein
may be readily adapted for any derivative in which the
C.sub.5H.sub.11 group is replaced by a different alkyl group. For
example, the invention provides corresponding embodiments in which
the C.sub.5H.sub.11 alkyl group is instead a linear or branched
C.sub.1-20 alkyl group or such a group having any subrange or
number of carbons therein. The invention also provides
corresponding embodiments in which one or more of the
C.sub.5H.sub.11 alkyl group and the available hydrogen positions of
the phenyl ring (together corresponding to positions R.sub.1
through R.sub.5 in the final compound generic formula printed
below) independently have, instead of said group or hydrogen
respectively, a linear or branched C.sub.1-20 alkyl group or such a
group having any subrange or number of carbons therein.
##STR00016##
[0028] It should also be understood that in this disclosure and the
appended claims where sequential reaction steps are graphically
depicted that the output of a reaction step is the input of the
next step. It should also be understood that wherever initial
reactants are shown, such reactants may be provided in a providing
step.
[0029] Any and all publications, patents, patent applications and
other documents cited in this application are hereby incorporated
by reference in their entireties for all purposes to the same
extent as if each individual publication, patent, patent
application or other document were individually indicated to be
incorporated by reference for all purposes.
[0030] While various specific embodiments have been illustrated and
described, it will be appreciated that various changes can be made
without departing from the spirit and scope of the invention(s).
Moreover, features described in connection with one embodiment of
the invention may be used in conjunction with other embodiments,
even if not explicitly exemplified in combination within.
* * * * *