A new organocatalyzed Michael-Michael cascade reaction generates highly substituted fused carbocycles.

While beta-ketoesters are useful Michael donors, they were previously ineffective in Michael-Michael cascade reactions using alpha,beta-unsaturated aldehydes in conjunction with diphenylprolinol silyl ether organocatalysts. However, through rational modification of substrates and manipulation of the catalytic cycle, we developed an efficient Michael-Michael cascade reaction using beta-ketoesters of type 9. In this transformation, highly substituted fused carbocycles are generated in a single step in up to 87% yield and 99% ee.