Diastereodivergent Synthesis of α-Chiral Tertiary Azides through Catalytic Asymmetric Michael Addition.

A diastereodivergent synthesis of α-chiral tertiary azides through catalytic enantioselective Michael addition of α-azido indanones to β,γ-unsaturated α-ketoesters is described. The merger of a newly designed bifunctional phosphoramide and hexafluoroisopropanol (HFIP) affords -adducts, whereas the use of thiourea provides -adducts without the aid of HFIP. Notably, additive HFIP proves to be the key control element to achieve diastereoselectivity reversal in the former case.

H-bond donor-directed switching of diastereoselectivity in the Michael addition of α-azido ketones to nitroolefins.

The development of catalyst-controlled stereodivergent asymmetric catalysis is important for providing facile access to all stereoisomers of chiral products with multiple stereocenters from the same starting materials. Despite progress, new design strategies for diastereodivergent asymmetric catalysis are still highly desirable. Here we report the potency of H-bond donors as the governing factor to tune diastereoselectivity in a highly diastereoselective switchable enantioselective Michael addition of α-azido ketones to nitroolefins.