U.S. patent application number 10/447082 was filed with the patent office on 2004-02-05 for preparation of epothilone intermediates.
Invention is credited to Hofle, Gerhard, Kim, Soong-Hoon, Vite, Gregory D..
Application Number | 20040023345 10/447082 |
Document ID | / |
Family ID | 22707682 |
Filed Date | 2004-02-05 |
United States Patent
Application |
20040023345 |
Kind Code |
A1 |
Vite, Gregory D. ; et
al. |
February 5, 2004 |
Preparation of epothilone intermediates
Abstract
The present invention relates to a process for the preparation
of intermediates useful in the synthesis of epothilone analogs by
initially enzymatically degrading certain epothilone compounds to
form ring-open structures containing a carboxyl group which is
esterified, the hydroxyl groups on the moiety protected and the
resulting compound oxidized by, e.g. ozone, to form a first
intermediate. The first intermediate can be reacted with a
triphenylphosphine adduct to yield a compound containing an ester
group at position 1 which is subsequently hydrolyzed to form a
second intermediate.
Inventors: |
Vite, Gregory D.;
(Titusville, NJ) ; Kim, Soong-Hoon; (Titusville,
NJ) ; Hofle, Gerhard; (Braunschweig, DE) |
Correspondence
Address: |
STEPHEN B. DAVIS
BRISTOL-MYERS SQUIBB COMPANY
PATENT DEPARTMENT
P O BOX 4000
PRINCETON
NJ
08543-4000
US
|
Family ID: |
22707682 |
Appl. No.: |
10/447082 |
Filed: |
May 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10447082 |
May 28, 2003 |
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09811808 |
Mar 19, 2001 |
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6593115 |
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60191975 |
Mar 24, 2000 |
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Current U.S.
Class: |
435/120 ;
548/181 |
Current CPC
Class: |
C12P 17/14 20130101;
C07D 277/30 20130101 |
Class at
Publication: |
435/120 ;
548/181 |
International
Class: |
C12P 017/14; C12P
007/64; C07D 417/02 |
Claims
What is claimed is:
1. A process for preparing a compound represented by formula I:
19wherein: X is selected from the group consisting of hydrogen,
alkyl, substituted alkyl, aryl and substituted aryl; R.sub.1 is
selected from the group consisting of hydrogen, alkyl, substituted
alkyl, aryl, substituted aryl, and heterocyclo; and P.sub.1 and
P.sub.2 are independently selected from the group consisting of
hydrogen, aralkyl, substituted aralkyl, trialkylsilyl,
triarylsilyl, dialkylarylsilyl, diarylalkylsilylalkoxyalkyl, and
aralkyloxyalkyl; comprising treating an epothilone compound of
formula III or formula IV: 20 wherein: X, R.sub.1, P.sub.1 and
P.sub.2 are as defined above; R.sub.2 is hydrogen, alkyl,
substituted alkyl, aryl, substituted aryl, heterocyclo or 21 and
R.sub.3 and R.sub.4 are selected from the group consisting of
hydrogen, alkyl, substituted alkyl, aryl, substituted aryl,
cycloalkyl and heterocyclo; with an enzyme to form a compound
represented by formula VI: 22 wherein R.sub.1 and R.sub.2 are as
defined above; optionally esterifying the carboxyl group of said
compound; optionally reacting the resulting esterified compound to
form protecting groups on the hydroxyl groups of said compound; and
reacting the resulting compound with a suitable oxidizing agent to
form said compound of formula I.
2. A process for preparing a compound represented by formula II:
23wherein: X is selected from the group consisting of hydrogen,
alkyl, substituted alkyl, aryl and substituted aryl; R.sub.1 is
selected from the group consisting of hydrogen, alkyl, substituted
alkyl, aryl, substituted aryl, and heterocyclo; R.sub.2 is
hydrogen, alkyl, substituted alkyl, aryl, substituted aryl,
heterocyclo or 24 and R.sub.3 and R.sub.4 are selected from the
group consisting of hydrogen, alkyl, substituted alkyl, aryl,
substituted aryl, cycloalkyl and heterocyclo; and P.sub.1, P.sub.2,
and P.sub.3 are independently selected from the group consisting of
hydrogen, aralkyl, substituted aralkyl, trialkylsilyl,
triarylsilyl, dialkylarylsilyl, diarylalkylsilylalkoxyalky- l, and
aralkyloxyalkyl; comprising reacting a compound represented by
formula I: 25 wherein X, R.sub.1, P.sub.1 and P.sub.2 are as
defined above; with a compound represented by formula IX: 26
wherein R.sub.2 and P.sub.3 are as defined above, to form a
compound represented by formula X: 27 and hydrolyzing the ester
group on said compound in the presence of a suitable base to form
said compound represented by formula II.
3. A process for preparing a compound represented by formula II:
28wherein: X is selected from the group consisting of hydrogen,
alkyl, substituted alkyl, aryl and substituted aryl; R.sub.1 is
selected from the group consisting of hydrogen, alkyl, substituted
alkyl, aryl, substituted aryl, and heterocyclo; R.sub.2 is
hydrogen, alkyl, substituted alkyl, aryl, substituted aryl,
heterocyclo or 29R.sub.3 and R.sub.4 are selected from the group
consisting of hydrogen, alkyl, substituted alkyl, aryl, substituted
aryl, cycloalkyl and heterocyclo; and P.sub.1, P.sub.2, and P.sub.3
are independently selected from the group consisting of hydrogen,
aralkyl, substituted aralkyl, trialkylsilyl, triarylsilyl,
dialkylarylsilyl, diarylalkylsilylalkoxyalky- l, and
aralkyloxyalkyl; comprising treating an epothilone compound of
formula III or formula IV: 30 with an enzyme to form a compound
represented by formula VI: 31esterifying the carboxyl group of said
compound; reacting the resulting esterified compound to form
protecting groups on the hydroxyl groups of said compound; reacting
the resulting compound with a suitable oxidizing agent to form a
compound represented by formula I: 32reacting said compound with a
compound represented by formula IX: 33to form a compound
represented by formula X: 34 and hydrolyzing the ester group on
said compound in the presence of a suitable base to form said
compound represented by formula II.
4. A process for preparing a compound represented by formula I:
35wherein: X is selected from the group consisting of hydrogen,
alkyl, substituted alkyl, aryl and substituted aryl; R.sub.1 is
selected from the group consisting of hydrogen, alkyl, substituted
alkyl, aryl, substituted aryl, and heterocyclo; and each P.sub.1
and P.sub.2 is, independently, selected from the group consisting
of hydrogen, aralkyl, substituted aralkyl, trialkylsilyl,
triarylsilyl, dialkylarylsilyl, diarylalkylsilylalkoxyalkyl, and
aralkyloxyalkyl; comprising treating an epothilone compound
represented by formula XV: 36 wherein: R.sub.1, P.sub.1 and P.sub.2
are as defined above; R.sub.2 is hydrogen, alkyl, substituted
alkyl, aryl, substituted aryl, heterocyclo or 37 and R.sub.3 and
R.sub.4 are selected from the group consisting of hydrogen, alkyl,
substituted alkyl, aryl, substituted aryl, cycloalkyl and
heterocyclo; with an enzyme to form a compound represented by
formula XVI: 38 wherein: R.sub.1, R.sub.2, P.sub.1 and P.sub.2 are
as defined above; and P.sub.3 is selected from the group consisting
of hydrogen, aralkyl, substituted aralkyl, trialkylsilyl,
triarylsilyl, dialkylarylsilyl, diarylalkylsilylalkoxyalkyl, and
aralkyloxyalkyl; esterifying the carboxyl group of compound of
formula XVI to form an ester compound represented by formula XVII:
39 wherein X, R.sub.1, R.sub.2, P.sub.1, P.sub.2 and P.sub.3 are as
defined above; hydrolyzing the ester compound to form a diol
compound of formula XVIII: 40 wherein X, R.sub.1, R.sub.2, P.sub.1,
P.sub.2 and P.sub.3 are as defined above; and reacting the diol
compound with a suitable oxidizing agent to form said compound of
formula I.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from provisional U.S.
Application Serial No. 60/191,975, filed Mar. 24, 2000,
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to an improved process for the
preparation of certain epothilone analogs.
BACKGROUND OF THE INVENTION
[0003] Epothilones are macrolide compounds that find utility in the
pharmaceutical field. For example, epothilones A and B having the
structures: 1
[0004] may be found to exert microtubule-stabilizing effects
similar to paclitaxel (TAXOL.RTM.) and hence cytotoxic activity
against rapidly proliferating cells, such as, tumor cells or other
hyperproliferative cellular disease, see Hofle, G., et al., Angew.
Chem. Int. Ed. Engl., Vol. 35, No.13/14, 1567-1569 (1996);
WO93/10121 published May 27, 1993; and WO97/19086 published May 29,
1997.
[0005] Derivatives and analogs of epothilones A and B have been
synthesized and may be used to treat a variety of cancers and other
abnormal proliferative diseases. Such analogs are disclosed in
Hofle et al., Id.; Nicolaou, K. C., et al., Angew. Chem. Int. Ed.
Engl. Vol. 36, No. 19, 2097-2103 (1997); and Su, D.-S., et al.,
Angew. Chem. Int. Ed. Engl., Vol. 36, No. 19, 2093-2097 (1997).
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a process for the
preparation of compounds represented by formulas I and II wherein
X, P.sub.1, P.sub.2, R.sub.1 and R.sub.2 are as defined below:
2
[0007] The compounds represented by formulas I and II are
intermediates for the preparation of epothilone analogs that are
useful in the treatment of a variety of cancers and other abnormal
proliferative diseases.
DETAILED DESCRIPTION OF THE INVENTION
[0008] The process of the present invention provides an
advantageous synthesis for the compounds represented by formulas I
and II 3
[0009] Compounds of formula I can be utilized to prepare, for
example, analogs represented by formula II which can, in turn, be
utilized to prepare epothilone analogs represented by the formulas
III and IV. 4
[0010] As used in the formulas I, II, III, IV and throughout the
specification, the symbols as given below have the following
meanings:
[0011] X is selected from the group consisting of hydrogen, alkyl,
substituted alkyl, aryl and substituted aryl;
[0012] R.sub.1 is selected from the group consisting of hydrogen,
alkyl, substituted alkyl, aryl, substituted aryl, and
heterocyclo;
[0013] R.sub.2 is hydrogen, alkyl, substituted alkyl, aryl,
substituted aryl, heterocyclo or 5
[0014] R.sub.3 and R.sub.4 are selected from the group consisting
of hydrogen, alkyl, substituted alkyl, aryl, substituted aryl,
cycloalkyl and heterocyclo;
[0015] P.sub.1, P.sub.2, P.sub.3 are independently selected from
the group consisting of hydrogen, aralkyl, substituted aralkyl,
trialkylsilyl, triarylsilyl, dialkylarylsilyl,
diarylalkylsilylalkoxyalkyl, and aralkyloxyalkyl.
[0016] Definitions
[0017] The following are definitions of various terms used herein
to describe this invention. These definitions apply to the terms as
they are used throughout this specification, unless otherwise
limited in specific instances, either individually or as part of a
larger group.
[0018] The term "alkyl" refers to optionally substituted straight-
or branched-chain saturated hydrocarbon groups having from 1 to 20
carbon atoms, preferably from 1 to 7 carbon atoms. The expression
"lower alkyl" refers to optionally substituted alkyl groups having
from 1 to 4 carbon atoms.
[0019] The term "substituted alkyl" refers to an alkyl group
substituted by, for example, one to four substituents, such as,
halo, trifluoromethyl, trifluoromethoxy, hydroxy, alkoxy,
cycloalkyoxy, heterocylooxy, oxo, alkanoyl, aryl, aryloxy, aralkyl,
alkanoyloxy, amino, alkylamino, arylamino, aralkylamino,
cycloalkylamino, heterocycloamino, disubstituted amino in which the
two substituents on the amino group are selected from alkyl, aryl,
aralkyl, alkanoylamino, aroylamino, aralkanoylamino, substituted
alkanoylamino, substituted arylamino, substituted aralkanoylamino,
thiol, alkylthio, arylthio, aralkylthio, cycloalkylthio,
heterocyclothio, alkylthiono, arylthiono, aralkylthiono,
alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, sulfonamido (e.g.
SO.sub.2NH.sub.2), substituted sulfonamido, nitro, cyano, carboxy,
carbamyl (e.g. CONH.sub.2), substituted carbamyl (e.g. CONH alkyl,
CONH aryl, CONH aralkyl or instances where there are two
substituents on the nitrogen selected from alkyl, aryl or aralkyl),
alkoxycarbonyl, aryl, substituted aryl, guanidino and heterocyclos,
such as, indolyl, imidazolyl, furyl, thienyl, thiazolyl,
pyrrolidyl, pyridyl, pyrimidyl and the like. Wherein, as noted
above, the substituents themselves are further substituted, such
further substituents are selected from the group consisting of
halogen, alkyl, alkoxy, aryl and aralkyl. The definitions given
herein for alkyl and substituted alkyl apply as well to the alkyl
portion of alkoxy groups.
[0020] The term "halogen" or "halo" refers to fluorine, chlorine,
bromine and iodine.
[0021] The term "aryl" refers to monocyclic or bicyclic aromatic
hydrocarbon groups having from 6 to 12 carbon atoms in the ring
portion, for example, phenyl, naphthyl, biphenyl and diphenyl
groups, each of which may be substituted.
[0022] The term "aralkyl" refers to an aryl group bonded to a
larger entity through an alkyl group, such as benzyl.
[0023] The term "substituted aryl" refers to an aryl group
substituted by, for example, one to four substituents such as
alkyl; substituted alkyl, halo, trifluoromethyl, trifluoromethoxy,
hydroxy, alkoxy, cycloalkyloxy, heterocyclooxy, alkanoyl,
alkanoyloxy, amino, alkylamino, dialkylamino, aralkylamino,
cycloalkylamino, heterocycloamino, alkanoylamino, thiol, alkylthio,
cycloalkylthio, heterocyclothio, ureido, nitro, cyano, carboxy,
carboxyalkyl, carbamyl, alkoxycarbonyl, alkylthiono, arylthiono,
alkysulfonyl, sulfonamido, aryloxy and the like. The substituent
may be further substituted by one or more members selected from the
group consisting of halo, hydroxy, alkyl, alkoxy, aryl, substituted
alkyl, substituted aryl and aralkyl.
[0024] The term "cycloalkyl" refers to optionally substituted
saturated cyclic hydrocarbon ring systems, preferably containing 1
to 3 rings and 3 to 7 carbons per ring, which may be further fused
with an unsaturated C.sub.3-C.sub.7 carbocyclic ring. Exemplary
groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,
cycloheptyl, cyclooctyl, cyclodecyl, cyclododecyl, and adamantyl.
Exemplary substituents include one or more alkyl groups as
described above, or one or more of the groups described above as
substituents for alkyl groups.
[0025] The terms "heterocycle", "heterocyclic" and "heterocyclo"
refer to an optionally substituted, unsaturated, partially
saturated, or fully saturated, aromatic or nonaromatic cyclic
group, for example, which is a 4 to 7 membered monocyclic, 7 to 11
membered bicyclic, or 10 to 15 membered tricyclic ring system,
which has at least one heteroatom in at least one carbon
atom-containing ring. Each ring of the heterocyclic group
containing a heteroatom may have 1, 2 or 3 heteroatoms selected
from nitrogen atoms, oxygen atoms and sulfur atoms, where the
nitrogen and sulfur heteroatoms may also optionally be oxidized and
the nitrogen heteroatoms may also optionally be quaternized. The
heterocyclic group may be attached at any heteroatom or carbon
atom.
[0026] Exemplary monocyclic heterocyclic groups include
pyrrolidinyl, pyrrolyl, indolyl, pyrazolyl, oxetanyl, pyrazolinyl,
imidazolyl, imidazolinyl, imidazolidinyl, oxazolyl, oxazolidinyl,
isoxazolinyl, isoxazolyl, thiazolyl, thiadiazolyl, thiazolidinyl,
isothiazolyl, isothiazolidinyl, furyl, tetrahydrofuryl, thienyl,
oxadiazolyl, piperidinyl, piperazinyl, 2-oxopiperazinyl,
2-oxopiperidinyl, 2-oxopyrrolidinyl, 2-oxazepinyl, azepinyl,
4-piperidonyl, pyridyl, N-oxo-pyridyl, pyrazinyl, pyrimidinyl,
pyridazinyl, tetrahydropyranyl, tetrahydrothiopyranyl,
tetrahydrothiopyranyl sulfone, morpholinyl, thiomorpholinyl,
thiomorpholinyl sulfoxide, thiomorpholinyl sulfone, 1,3-dioxolane
and tetrahydro-1,1-dioxothienyl, dioxanyl, isothiazolidinyl,
thietanyl, thiiranyl, triazinyl, and triazolyl, and the like.
[0027] Exemplary bicyclic heterocyclic groups include
benzothiazolyl, benzoxazolyl, benzothienyl, quinuclidinyl,
quinolinyl, quinolinyl-N-oxide, tetrahydroisoquinolinyl,
isoquinolinyl, benzimidazolyl, benzopyranyl, indolizinyl,
benzofuryl, chromonyl, coumarinyl, cinnolinyl, quinoxalinyl,
indazolyl, pyrrolopyridyl, furopyridinyl (such as
furo[2,3-c]pyridinyl, furo[3,1-b]pyridinyl] or
furo[2,3-b]pyridinyl), dihydroisoindolyl, dihydroquinazolinyl (such
as 3,4-dihydro-4-oxo-quinazolinyl), benzisothiazolyl,
benzisoxazolyl, benzodiazinyl, benzofurazanyl, benzothiopyranyl,
benzotriazolyl, benzpyrazolyl, dihydrobenzofuryl,
dihydrobenzothienyl, dihydrobenzothiopyranyl,
dihydrobenzothiopyranyl sulfone, dihydrobenzopyranyl, indolinyl,
isochromanyl, isoindolinyl, naphthyridinyl, phthalazinyl,
piperonyl, purinyl, pyridopyridyl, quinazolinyl,
tetrahydroquinolinyl, thienofuryl, thienopyridyl, thienothienyl,
and the like.
[0028] Exemplary substituents for the terms "heterocycle,"
"heterocyclic," and "heterocyclo" include one or more substituent
groups as described above for substituted alkyl or substituted
aryl, and smaller heterocyclos, such as, epoxides, aziridines and
the like.
[0029] The term "alkanoyl" refers to --C(O)-alkyl.
[0030] The term "substituted alkanoyl" refers to --C(O)-substituted
alkyl.
[0031] The term "heteroatoms" shall include oxygen, sulfur and
nitrogen.
[0032] The compounds represented by formulas I, II, III, UV above
may exist as multiple optical, geometric, and stereoisomers. While
the compounds shown herein are depicted for one optical
orientation, included within the present invention are all isomers
and mixtures thereof.
[0033] Use and Utility
[0034] The compounds represented by formulas III and IV above are
microtubule-stabilizing agents. The compounds, and thus the
process, are useful in the treatment of a variety of cancers and
other proliferative diseases including, but not limited to, the
following:
[0035] carcinoma, including that of the bladder, breast, colon,
kidney, liver, lung, ovary, pancreas, stomach, cervix, thyroid and
skin, including squamous cell carcinoma;
[0036] hematopoietic tumors of lymphoid lineage, including
leukemia, acute lymphocytic leukemia, acute lymphoblastic leukemia,
B-cell lymphoma, T-cell lymphoma, Hodgkins lymphoma, non-Hodgkins
lymphoma, hairy cell lymphoma and Burketts lymphoma;
[0037] hematopoietic tumors of myeloid lineage, including acute and
chronic myelogenous leukemias and promyelocytic leukemia;
[0038] tumors of mesenchymal origin, including fibrosarcoma and
rhabdomyoscarcoma;
[0039] other tumors, including melanoma, seminoma, teratocarcinoma,
neuroblastoma and glioma;
[0040] tumors of the central and peripheral nervous system,
including astrocytoma, neuroblastoma, glioma, and schwannomas;
[0041] tumors of mesenchymal origin, including fibrosarcoma,
rhabdomyoscaroma, and osteosarcoma; and
[0042] other tumors, including melanoma, xeroderma pigmentosum,
keratoacanthoma, seminoma, thyroid follicular cancer and
teratocarcinoma.
[0043] The compounds represented by formulas III and IV above will
also inhibit angiogenesis, thereby affecting the growth of tumors
and providing treatment of tumors and tumor-related disorders. Such
anti-angiogenesis properties of the compounds represented by
formulas III and IV will also be useful in the treatment of other
conditions responsive to anti-angiogenesis agents including, but
not limited to, certain forms of blindness related to retinal
vascularization, arthritis, especially inflammatory arthritis,
multiple sclerosis, restinosis and psoriasis.
[0044] Compounds represented by formulas III and IV will induce or
inhibit apoptosis, a physiological cell death process critical for
normal development and homeostasis. Alterations of apoptotic
pathways contribute to the pathogenesis of a variety of human
diseases. Compounds represented by formulas III and IV, as
modulators of apoptosis, will be useful in the treatment of a
variety of human diseases with aberrations in apoptosis including,
but not limited to cancer, particularly but not limited to,
follicular lymphomas, carcinomas with p53 mutations, hormone
dependent tumors of the breast, prostrate and ovary, and
precancerous lesions such as familial adenomatous polyposis, viral
infections including but not limited to herpesvirus, poxvirus,
Epstein-Barr virus, Sindbis virus and adenovirus, autoimmune
diseases such as systemic lupus erythematosus, immune mediated
glomerulonephritis, rheumatoid arthritis, psoriasis, inflammatory
bowel diseases and autoimmune diabetes mellitus; neurodegenerative
disorders such as Alzheimer's disease, AIDS-related dementia,
Parkinson's disease, amyotrophic lateral sclerosis, retinitis
pigmentosa, spinal muscular atrophy and cerebellar degeneration;
AIDS; myelodysplastic syndromes; aplastic anemia; ischemic injury
associated myocardial infarctions; stroke and reperfusion injury;
restenosis; arrhythmia; atherosclerosis; toxin-induced or alcohol
induced liver diseases; hematological diseases such as chronic
anemia and aplastic anemia; degenerative diseases of the
musculoskeletal system such as osteoporosis and arthritis;
aspirin-sensitive rhinosinusitis; cystic fibrosis; multiple
sclerosis; kidney diseases; and cancer pain.
[0045] The compounds represented by formulas III and IV are also
useful in combination with known anti-cancer and cytotoxic agents
and treatments, including radiation. If formulated as a fixed dose,
such combination products employ the compounds represented by
formulas III and IV within the dosage range described below and the
other pharmaceutically active agent within its approved dosage
range. Compounds represented by formulas III and IV can be used
sequentially with known anticancer or cytotoxic agents and
treatment, including radiation when a combination formulation is
inappropriate. Especially useful are cytotoxic drug combinations
wherein the second drug chosen acts in a different phase of the
cell cycle, e.g. S phase, than the present compounds represented by
formulas III and IV which exert their effects at the G.sub.2-M
phase.
[0046] The compounds prepared in accordance with the present
invention can be formulated with a pharmaceutical vehicle or
diluent for oral, intravenous or subcutaneous administration. Such
pharmaceutical compositions can be formulated in a classical manner
well known to those of ordinary skill in the art using solid or
liquid vehicles, diluents and additives appropriate to the desired
mode of administration. Orally, the compounds can be administered
in the form of tablets, capsules, granules, powders and the like.
The compounds are administered in a dosage range of about 0.05 to
200 mg/kg/day, preferably less than 100 mg/kg/day, in a single dose
or in 2 to 4 divided doses.
[0047] Methods of Preparation
[0048] The intermediate compounds represented by formulas I and II
are prepared from epothilone compounds represented by formula V in
Scheme 1, particularly epothilone C or D wherein R.sub.1 is as
defined above. The epothilone starting materials will fall under
the general formulas III and IV as shown above. The advantage of
the subject process is that it can be utilized to transform
epothilone compounds that may have less than optimum properties
into other analogs that have more desirable properties. The
epothilone starting materials represented by formula V and formula
XV are known compounds. See, for example, Kim et al., Org. Lett.,
2, 1537 (2000); Hofle et al., Angew. Chem. Int. Ed. Engl., 35,
1567-1569 (1996); WO 93/10121 published May 27, 1993; and WO
97/19086 published May 29, 1997; Nicolaou et al., Angew Chem. Int.
Ed. Engl., 36, 2097-2103 (1997); and Su et al., Angew Chem. Int.
Ed. Engl., 36, 2093-2097 (1997).
[0049] As illustrated in Scheme 1, the epothilone starting material
V is treated with a suitable enzyme that causes the molecule to
degrade to yield a compound represented by formula VI as
illustrated in Scheme 1. Suitable enzymes include, without intended
limitation, pig liver esterase, chymotrypsin, or pancreatin. The
carboxyl moiety of the compound represented by formula VI is then
esterified to form an ester represented by formula VII by treatment
with an alkylating agent such as diazomethane, trimethylsilyl
diazomethane, or an alkyl halide. In the reaction illustrated in
Scheme 1, trimethylsilyldiazomethane is utilized as the alkylating
agent to form the methyl ester of the carboxyl moiety.
[0050] The ester compounds represented by formula VII are then
treated to form protecting groups, such as silanes, on the hydroxyl
groups. This is carried out by reaction with suitable agents such
as trialkylsilyl halides, triflates, i.e. trifluoromethane
sulfonates, to form a compound represented by formula VIII wherein
P.sub.1, P.sub.2 and/or P.sub.3 are as defined above. A preferred
reagent for forming the protecting groups on the hydroxyls is
t-butyldimethylsilyl trifluoromethanesulfonate. The compounds
represented by formula VIII are then oxidized, e.g. by ozone, to
cleave the olefin at position 12, thereby forming the subject
intermediate compounds represented by formula I.
[0051] The intermediate compounds of the present invention
represented by formula I are suitably converted to the subject
intermediate compounds represented by formula II in two steps as
shown in Scheme 1. In the first step, the compound represented by
formula I is reacted with a suitable Wittig type reagent
represented by the following formula 6
[0052] wherein R.sub.2 and P.sub.3 are as defined above,
illustrated by formula IX in Scheme 1. The reagents represented by
formula IX can be prepared, for example, as described by Nicolaou
et al., Angew. Chem., Vol. 110, No. 85 (1998). The reaction of the
compound represented by formula IX and the compound represented by
formula I in Scheme 1 is an ester represented by formula X in
Scheme 1. The ester moiety at position 1 of the compounds
represented by formula X is then hydrolyzed by methods well know in
the art, e.g. treatment with a suitable base, such as aqueous
hydroxides or carbonates, to yield the carboxylic acids represented
by formula II. 78
[0053] Compounds of formula II and methods for synthesizing
epothilone analogs from such compounds are known. See, Nicolaou et
al., J. Amer. Chem. Soc., 119, 7974 (1997). The protected hydroxyl
groups of compounds of formula II may be deprotected according to
several known procedures. See, Greene and Wuts, "Protective Groups
In Organic Synthesis," 2.sup.nd Ed., John Wiley & Sons, Inc.,
New York, 1991.
[0054] Intermediate compound represented by formula I can also be
prepared according to the procedures depicted in Scheme 2. 9
[0055] As illustrated in Scheme 2, the epothilone starting material
XV is treated with a suitable enzyme that cleaves the compound of
formula XV to form a compound of formula XVI bearing a carboxyl
group. Suitable enzymes include, but are not limited to, pig liver
esterase, chymotrypsin or pancreatin. The carboxyl group of
compound XVI is then esterified with an alkylating agent to form
the ester compound XVII. Examples of alkylating agents include, but
are not limited to, diazomethane, trimethylsilyl diazomethane or an
alkyl halide. As an example, in the reaction depicted in Scheme 2,
diazomethane is used as the alkylating agent. The ester compound
XVII is next hydrolyzed to form a diol compound of formula XVIII.
This hydrolysis step is performed under acidic conditions. Finally,
compound XVIII is oxidized to form the intermediate of formula I.
An example of an oxidizing agent is sodium periodate. Other
examples include, but are not limited to, Ca(OCl).sub.2,
NaBiO.sub.3, I(OAc).sub.3, HIO.sub.4, Amberlite and 904-NaIO.sub.4
(J. Chem. Soc. Perkin I, 509 (1982)), Pb(OAc).sub.2, HgO and
I.sub.2, MnO.sub.2, KmnO.sub.4, H.sub.2CrO.sub.4, PCC (Syn.
Commun., 12, 833 (1982)), RuCl.sub.2 (PPh.sub.3).sub.3 and
BaMnO.sub.4.
[0056] The compounds represented by formulas I and II are useful as
intermediates in the preparation of epothilone analogs
characterized by enhanced activity.
[0057] All references cited herein are incorporated by reference as
if set forth at length herein.
[0058] The following non-limiting examples serve to illustrate the
practice of the invention.
EXAMPLE 1
[0059] Preparation of a Compound Represented by the Formula 10
[0060] A solution of epothilone C, representative of formula V in
Scheme 1 (8.4 mg, 0.017 mmol) in 125 .mu.L dimethylsulfoxide was
diluted with 5.0 mL of pH 7 phosphate buffer. Pig liver esterase
(200 units in 50 .mu.L of 3.2 M aqueous (NH.sub.4).sub.2SO.sub.4)
was added, and the suspension was stirred at 37.degree. C. for 18
hours. TLC showed that epothilone C was completely consumed. The
reaction was stored at -34.degree. C. for 12 days. The mixture was
acidified to pH about 4.5 with 1 N HCl and then extracted with two
5 mL portions of dichloromethane. The organic phase was dried over
Na.sub.2SO.sub.4, concentrated under vacuum, and purified by flash
chromatography on silica gel eluting with 1% acetic acid in ethyl
acetate to provide 2.1 mg (25%) of the compound of the formula
given above, representative of formula VI in Scheme 1, as a clear
film. MS (ESI.sup.+): 496 (M+H).sup.+; MS (ESI.sup.-): 494
(M-H).sup.-
EXAMPLE 2
[0061] Preparation of a Compound Represented by the Formula 11
[0062] A solution of the compound formed in Example 1 (1 mg, 0.0020
mmol) in 0.5 mL of a mixture of 2:7 methanol:toluene was treated
with two drops of trimethylsilyl diazomethane at 25.degree. C.
After 10 minutes, TLC showed that the starting material had been
converted to a new UV active component. The reaction was
concentrated under vacuum and purified by flash chromatography on
silica gel eluting with a gradient of 60-100% ethyl acetate in
hexane to provide 1 mg (100%) of the compound given above formula
given above, representative of formula VII in Scheme 1, as a clear
film. MS (ESI.sup.+): 510 (M+H).sup.+; MS (ESI.sup.-): 508
(M-H).sup.-
EXAMPLE 3
[0063] Preparation of a Compound Represented by the Formula 12
[0064] To a solution of the compound formed in Example 2 (20.4 mg,
0.04 mmol) in 2.0 mL anhydrous dichloromethane at -14.degree. C.
was added 2,6-lutidine (23 .mu.L, 0.2 mmol, 5 eq).
t-Butyldimethylsilyl triflate (32 .mu.L, 0.14 mmol, 3.5 eq) was
added dropwise to the reaction. After 30 minutes, additional
2,6-lutidine (33 .mu.L, 0.28 mmol, 7 eq) and t-butyldimethylsilyl
triflate (65 .mu.L, 0.28 mmol, 75 eq) were added. After 12 hours,
TLC indicated that the starting material had been consumed.
Saturated aqueous NaHCO.sub.3 (5 mL) was added and the reaction was
extracted with two 5 mL portions of dichloromethane. The organic
phase was dried over Na.sub.2SO.sub.4, concentrated under vacuum,
and purified by flash chromatography on silica gel eluting with 10%
ethyl acetate in petroleum ether to provide 15 mg (44%) of the
compound given above, representative of compound VIII in Scheme 1,
as a clear film. MS (ESI.sup.+): 838 (M+H--CH.sub.3).sup.+
EXAMPLE 4
[0065] Preparation of a Compound Represented by the Formula 13
[0066] A solution of the compound formed in Example 3 (6.4 mg,
0.0075 mmol) in 2.0 mL anhydrous dichloromethane was cooled to
-78.degree. C. Ozone was passed through the solution for
approximately 2 minutes, during which time the solution became
light blue. Triphenylphosphine (8 mg, 0.03 mmol, 4 eq) was added
and the reaction mixture was warmed to room temperature over 30
minutes. The reaction mixture was concentrated under vacuum and
purified by flash chromatography on silica gel eluting with 10%
ethyl acetate in petroleum ether to provide 3.6 mg (86%) of the
compound given above, representative of compound I of the present
invention, as a clear film. MS (ESI.sup.+): 559 (M+H).sup.+
[0067] Preparation of a Compound Represented by the Formula 14
[0068] As a separate step, the compound given above, representative
of compound IX in Scheme 1, was prepared as described by Nicolaou
et al., Angew. Chem., 1998, 110, 85. MS (ESI.sup.+): 572
(M+H).sup.+
EXAMPLE 5
[0069] Preparation of a Compound Represented by the Formula 15
[0070] A solution of the compound formed in Example 4 according to
the method taught by Nicolaou et al. (18 mg, 0.013 mmol, 2 eq) in
0.5 mL anhydrous tetrahydrofuran was cooled to 0.degree. C. Sodium
bis(trimethylsilyl)amide (31 .mu.L, 31 .mu.mol, 2.4 eq) was added
and the solution became brown. The reaction was cooled to
20.degree. C. and the compound formed in Example 4 representative
of formula I of the present invention (7.3 mg, 0.013 mmol, 1 eq) in
0.5 mL tetrahydrofuran was added. After 10 minutes, the reaction
was quenched with 4 mL of saturated aqueous NaHCO.sub.3 and
extracted with two 2 mL portions of dichloromethane. The organic
phase was dried over Na.sub.2SO.sub.4, concentrated under vacuum,
and purified by flash chromatography on silica gel eluting with 10%
ethyl acetate in petroleum ether to provide 6 mg (55%) of the
compound given above, representative of compound X in Scheme 1, as
a clear oil. MS (ESI.sup.+): 852 (M+H).sup.+; 874 (M+Na).sup.+
EXAMPLE 6
[0071] Preparation of a Compound Represented by the Formula 16
[0072] A solution of the ester compound prepared in Example 5 (2.2
mg, 0.0026 mmol) in 0.5 mL t-butyl alcohol/water (2:1) was treated
with aqueous 1.0 M LIOH (40 .mu.L, 0.039 mmol, 15 eq). The reaction
was stirred for 48 hours at room temperature. TLC indicated that
the reaction was approximately 50% complete. The reaction was
purified by flash chromatography on silica gel eluting with 10%
ethyl acetate in hexane with 1% acetic acid to provide 1 mg (46%)
of the compound given above, representative of compound II of the
present invention.
EXAMPLE 7
[0073] Preparation of the Compound Represented by the Formula XIV
(Scheme 3): 17 18
[0074] (i) Preparation of compound of formula XI: Epothilone A (0.5
g, 1.01 mmol) was dissolved in 0.2 mL of DMSO and 300 mL of
phosphate buffer (20 mmol, pH 7.4). Pig liver esterase (50 mg) was
added to the epothilone A solution, with stirring. After stirring
for 3 days, residual lactone was extracted with 50 mL of a 1:1
mixture of hexanes and ethyl acetate. The aqueous phase was
adjusted to pH 5 and extracted three times with ethyl acetate. The
organic layer was dried with MgSO.sub.4, filtered and evaporated.
Yield: 0.55 g of compound XI was obtained as a viscous oil
containing 10% of solvents.
[0075] (ii) Preparation of compound of formula XII: Compound XI (60
mg) obtained above was dissolved in ethyl acetate. To this, excess
diazomethane in diethyl ether was added. The conversion was
complete in 15 minutes. The solvents were evaporated in vacuo to
yield 50 mg of ester compound XII as a colorless viscous oil.
[0076] (iii) Preparation of compound of formula XIII: Compound XII
(23 mg) was dissolved in THF (0.5 mL). To this solution, was added
concentrated sulfuric acid (50 mg) dissolved in 1 mL of H.sub.2O,
with stirring. After one hour, the pH was adjusted to 7 with sodium
bicarbonate, and the mixture extracted three times with ethyl
acetate. The organic extract was evaporated to provide 21 mg of
crude diol compound XIII as a mixture of stereoisomers.
[0077] .sup.1H-NMR (CD.sub.3OD): 7.20, 7.21 (s, 19-H), 6.68, 6.63
(s, 17-H), 4.33 (dd, 3-H), 4.40, 3.76, 3.53, 3.47, 3.36 (m, 7-H,
12-H, 13-H), 3.72 (s, OMe), 2.72 (s, 21-H.sub.3), 2.48, 2.37 (ddd,
2-H.sub.2), 2.00, 2.02 (s, 16-Me), 1.8-1.3 (m, 8-H, 9-H.sub.2,
10-H.sub.2, 11-H.sub.2), 1.21, 1.18 (s, 4-(CH.sub.3).sub.2), 1.12
(d, 6-Me), 0.96 (d, 8-Me).
[0078] (iv) Preparation of compound of formula XIV: Diol XIII (23
mg) was dissolved in 0.6 mL of THF. To this solution was added
sodium periodate (7 mg) in 1.2 mL of H.sub.2O, with stirring. After
30 minutes, the solvents were evaporated in vacuo and the residue
purified by preparative HPLC (Nucleosil RP 18, methanol/water
gradient 35:65 to 60:40). The fraction containing compound XIV was
concentrated in vacuo and extracted with n-butanol. Evaporation of
the organic layer provided 12 mg of the aldehyde compound XIV.
[0079] .sup.1H-NMR (CDCl.sub.3): 9.76 (t, 12-H), 4.25 (dd, 3-H),
3.73 (s, OCH.sub.3), 3.38 (dd, 7-H), 3.25 (dq, 6-H), 2.3 2.5 (m,
2-H.sub.2, 11-H.sub.2), 1.75 (m, 8-H), 1.55 (m, 9-H.sub.2,
10-H.sub.2, 11-H.sub.2), 1.19, 1.13 (4-(CH.sub.3).sub.2), 1.06 (d,
6-CH.sub.3), 0.87 (d, 8-CH.sub.3).
[0080] ESI-MS (pos. ions): m/z=357 (M+H.sup.++MeOH).
* * * * *