One-Pot Organocatalytic Enantioselective Michael-Michael-Aldol-Henry Reaction Cascade. A Facile Entry to the Steroid System with Six Contiguous Stereogenic Centers

An expedited method has been developed for the enantioselective synthesis of highly functionalized steroid systems containing six contiguous stereogenic centers with high enantioselectivities (99% ee). The one-pot methodology comprises a cascade of organocatalytic Michael-Michael-aldol-Henry reactions of 7-nitrohept-3-en-2-one and 5-(1-methyl-2,5-dioxocyclopentyl)pent-2-enal. The structure and absolute configuration of the products were confirmed by X-ray analyses of appropriate products.