Aldol chiral hydrogen bond donors

Chiral hydrogen bond donors in enantioselective aldol reactions ... [Pg.131]

Malonic acid half thioesters, H02C-CH(R )-C0-SR (R =H/Me), undergo an enantioselective decarboxylative aldol reaction with aldehydes, using a chiral catalyst bearing a hydrogen-bond donor and acceptor. In situ ESI-MS evidence supports a complex between the conjugate base of the substrate and the conjugate acid of the... [Pg.27]

Since the discovery of proline-catalyzed enantioselective aldol reactions, an extensive research program to explore chiral secondary amine catalysts has been pursued. Several polymer-supported chiral amines have been synthesized for aldol, Mannich, and related reactions. Polystyrene is a popular solid phase for use in place of silica gel in the proline-based organocatalysis. In contrast, silica gel displays a slightly acidic character and has a hydrogen-bond donor or acceptor, which may change the catalytic activity and chiral space of the organocatalyst. Flow enantioselective aldol [158-161], Mannich [162], Michael [163], and related reactions... [Pg.185]