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A Tandem Metal Carbene Cyclization−Cycloaddition Approach to the Pseudolaric Acids

2003; American Chemical Society; Volume: 68; Issue: 11 Linguagem: Inglês

10.1021/jo026399m

1520-6904

Bin Chen, Rebecca Y. Y. Ko, Mabel S. M. Yuen, Kin‐Fai Cheng, Pauline Chiu,

Cyclopropane Reaction Mechanisms

An approach toward the synthesis of the antifungal and cytotoxic pseudolaric acids based on the tandem metal carbene cyclization-cycloaddition reaction is described. Using this strategy, the advanced intermediate 3a bearing three of the four stereocenters of the target molecules has been synthesized. The substrate-controlled diastereoselectivity of the tandem carbene cyclization-cycloaddition was preferential for the undesired diastereomer, but reagent control through the use of Hashimoto's chiral rhodium catalyst Rh(2)(S-BPTV)(4) reversed the selectivity in favor of 3a. Ring opening of the oxabicyclic nucleus to give a hydroxycycloheptene has been demonstrated in a model study.