Organocatalytic Enantioselective Michael-Acetalization-Reduction-Nef Reaction for a One-Pot Entry to the Functionalized Aflatoxin System. Total Synthesis of (-)- Dihydroaflatoxin D2 and (-)- and (+)-Microminutinin

An efficient method has been developed for the enantioselective synthesis of the aflatoxin system with multiple stereocenters via a sequence of organocatalytic Michael-acetalization-reduction-Nef reactions that proceed with high enantioselectivities (90-99% ee). The one-pot reaction sequence provides a facile entry to the aflatoxin system, including dihydroaflatoxin D2, which includes a formal total synthesis of aflatoxin B2. The first total synthesis of (-)- and (+)-microminutinin was also achieved via this protocol.