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.