Organocatalytic synthesis of multiple substituted bicyclo[4.4.0]decalin system.

An efficient and unprecedented organocatalytic reaction of γ-nitroketones with α,β-unsaturated aldehydes to give polyfunctionalized [4.4.0] bicyclic skeletons was developed. The diphenylprolinol silyl ether mediated nitro-Michael/Aldol reaction afforded the hexa-substituted decalin carboaldehydes with excellent diastereo- and enantioselectivity (up to >99:1 dr and >99% ee) via a formal [4 + 2] carbocyclization process.