Chemical & Pharmaceutical Bulletin 1997-12-01

Construction of AB-ring system of taxane framework by A-ring annulation strategy: synthesis of 1-hydroxy-8,11,11-trimethylbicyclo-[5.3.1]undec-7-en-9-one by way of intramolecular aldol cyclization to form the C1-C10 bond.

K Yamada, H Iwadare, T Mukaiyama

Index: Chem. Pharm. Bull. 45(12) , 1898-905, (1997)

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Abstract

Construction of the AB-ring system of the taxane framework via an A-ring annulation strategy was demonstrated by base-mediated intramolecular aldol reaction of (Z)-2,2-dimethyl-3-(1-methyl-2-oxopropylidene)cyclooctanone, affording the title compound, 1-hydroxy-8,11,11-trimethylbicyclo[5.3.1]undec-7-en-9-one. A cyclization precursor, the tetra-substituted (Z)-alkene, was prepared from the corresponding cyclooctanone derivative, 3-[(alpha,alpha- dimethylbenzyl)dimethylsiloxy]-2,2-dimethylcyclooctanone via a bicyclic alpha,beta-unsaturated lactone intermediate.