Asymmetric Organocatalytic Synthesis of 2,3-Allenamides from Hydrogen-Bond-Stabilized Enynamides.

Abstract

Asymmetric catalytic synthesis of 2,3-allenamides from hydrogen-bond-stabilized enynamides in the presence of quinine-based bifunctional squaramide organocatalysts is described. This protocol forms a variety of 2,3-allenamides in high yields and excellent stereoselectivities, in which the elaborated introduction of intramolecular H-bonds within the N, N-bidentate amide group constitutes one of the keys to this highly enantioselective transformation. The synthetic practicality of this reaction has been demonstrated by the axis-to-center chirality transfer of allenamides to furnish enantiomerically enriched building blocks.