- Asymmetric total synthesis of Taxol
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The asymmetric total synthesis of Taxol was achieved by way of B to BC to ABC to ABCD ring construction. Optically active 8-membered ring enones 1 and 2 corresponding to the B ring of Taxol have been synthesized in high yields from the linear precursors 28 and 32, respectively, by intramolecular aldol cyclization using SmI2. The optically active linear polyoxy compounds 28 and 32 were obtained by way of diastereoselective aldol reaction between aldehyde 4 and ketene silyl acetal 8 catalyzed by MgBr2 · OEt2. The chiral pentanal 4 was synthesized either by asymmetric aldol reaction of achiral aldehyde 7 and ketene silyl acetal 8 by means of a chiral Lewis acid or by diastereoselective aldol reaction between the chiral aldehyde 16, derived from L-serine, and the lithium enolate derived from methyl isobutyrate. Optically active bicyclo[6.4.0]dodecanone 38β, corresponding to the BC ring system of Taxol, was prepared from 8-membered ring enone 2 in high yield by stereoselective Michael addition and successive intramolecular aldol cyclization. Furthermore, baccatin III, the ABCD ring system of Taxol, was efficiently synthesized from the BC ring system 38β by successive construction of the A and D rings by intramolecular pinacol coupling cyclization, introduction of the C-13 hydroxyl group and an oxetane-forming reaction. Finally, the total synthesis of Taxol was accomplished by dehydration condensation between a protected N-benzoylphenylisoserine 70 or 75 and 7-TES baccatin III, prepared from baccatin III. Taxol side chains 70, 73, 75, and 77, optically active protected N-benzoylphenylisoserines, were synthesized by enantioselective aldol reaction from two achiral starting materials, benzaldehyde and an enol silyl ether 65 derived from S-ethyl benzyloxyethanethioate.
- Mukaiyama, Teruaki,Shiina, Isamu,Iwadare, Hayato,Saitoh, Masahiro,Nishimura, Toshihiro,Ohkawa, Naoto,Sakoh, Hiroki,Nishimura, Koji,Tani, Yu-Ichirou,Hasegawa, Masatoshi,Yamada, Koji,Saitoh, Katsuyuki
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p. 121 - 161
(2007/10/03)
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- Process for the preparation of a 1,3-oxazolidine-5-carboxylic acid
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Method for the preparation of 1,3-oxazolidin 5-carboxylic acid having the general formula (I) STR1 from a product having the general formula (II) STR2 In the general formulas (I) and (II), Ar is an aryl radical, R1 is a benzoyl radical or a rad
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- Total asymmetric synthesis of taxol by dehydration condensation between 7-TES baccatin III and protected N-benzoylphenylisoserines prepared by enantioselective aldol reaction
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Total asymmetric synthesis of Taxol was completed by dehydration condensation between a protected N-benzoylphenylisoserine 4 or 9 and 7-TES baccatin in which was prepared from 8-membered ring enone. Taxol side chains 4, 7, 9 and 11, optically active protected N-benzoylphenylisoserines, were successfully synthesized by enantioselective aldol reaction from two achiral starting materials, benzaldehyde and an enol silyl ether derived from S-ethyl benzyloxyethanethioate.
- Shiina, Isamu,Saitoh, Katsuyuki,Frechard-Ortuno, Isabelle,Mukaiyama, Teruaki
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- Process for preparing taxane derivatives
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Method of preparing taxane derivatives of general formula (I) by esterification of protected baccatine III or 10-deacetyl-baccatine III by means of an acid of general formula (VII), deprotection of the side chain and elimination of the hydroxy function protection groupings. In general formulae (I) and (VII): Ar stands for aryl, R is hydrogen or acetyl, R1 is benzoyl or R2 --O--CO-- in which R2 is alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, bicycloalkyl, phenyl or heterocyclyl, and R3 is hydrogen, alkoxy, optionally substituted aryl. STR1
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- Direct, Stereoselective Synthesis of the Protected Paclitaxel (Taxol) Side Chain and High-yield Transformation to Paclitaxel
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A short, efficient approach to the p-methoxybenzylidene-protected paclitaxel (Taxol) side chain through benzaldehyde benzoylimine-chiral enolate condensation, followed by DDQ-mediated oxazolidine formation and hydrolysis is described; the C-7-triethylsily
- Kanazawa, Alice M.,Denis, Jean-Noel,Greene, Andrew E.
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p. 2591 - 2592
(2007/10/02)
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