A New Organocatalyzed Michael−Michael Cascade Reaction Generates Highly Substituted Fused Carbocycles

While β-ketoesters are useful Michael donors, they were previously ineffective in Michael−Michael cascade reactions using α,β-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 β-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.