Enantioselective and regioselective organocatalytic conjugate addition of malonates to nitroenynes.

The first catalytic asymmetric conjugate addition of 1,3-dicarbonyl compounds to nitroenynes catalyzed by cinchona alkaloid-based thiourea organocatalysts has been developed. The 1,4-addition adducts were obtained solely, in moderate to good yields (up to 93%) with good enantioselectivities (up to 99% ee). This protocol affords a conceptually different entry to the precursors of pharmaceutically important chiral β-alkynyl acid derivatives and synthetically useful chiral nitroalkynes. Notably, the protocol worked well with both aryl- and alkyl-substituted alkynyl substrates.