Enantio- and Diastereoselective Organocatalytic Conjugate Additions of Nitroalkanes to Enone Diesters

Enantio-
and diastereoselective conjugate addition reactions between
nitroethane or nitropropane and enone diesters are reported. A bifunctional
triaryliminophosphorane catalyzed the addition reaction with consistently
excellent stereoselectivities and yields across a wide range of substrates.
By the use of the gem-diester functional handle present
in the adducts, local desymmetrization via diastereotopic group discrimination
was demonstrated, and a polyfunctionalized lactam with three contiguous
stereocenters was synthesized.