Synthesis of (2 R ,3 S )-isobutyl phenylisoserinate, the Taxol ® side chain, from ethyl benzoylacetate
摘要:
Reduction of ethyl 2-chloro-3-phenyl-3-oxopropionate with borohydride affords predominately the synchlorohydrin. Resolution of this ester with the lipase MAP-10 gives (2S,3R)-2-chloro-3-hydroxypropionic acid which after esterification with MeOH/HCl is converted to the cis-epoxide with potassium carbonate and DMF. Aminolysis of the epoxide with aqueous ammonia results in ring opening and amide formation. The amide is converted to an ester upon treatment with isobutyl alcohol and HCl(g) at 100 degrees C. Neutralization then affords the Taxol side chain as the free amine. (C) 2000 Published by Elsevier Science Ltd.
The invention is novel intermediates useful in producing taxol. These include the oxazolidine ester (III) ##STR1## the oxazolidine acid (IV) ##STR2## and the oxazolidine (XI) ##STR3##
A general preparation of chiral ruthenium(II) catalysts and the homogeneous enantioselective hydrogenation of prochiral olefins and keto groups are presented. Some applications to the synthesis of biologically active compounds are reported. (C) 1998 Elsevier Science S.A. All rights reserved.
CABALEIRO, MERCEDES C.;GARAY, RAUL O., J. CHEM. SOC. PERKIN TRANS.,(1987) N 10, 1473-1476