Highly stereoselective formal
[formula: see text] Highly stereoselective formal [3 + 3] cycloaddition reactions of chiral vinylogous amides with alpha, beta-unsaturated iminiums are described. A mechanistic model is proposed to rationalize the observed stereoselectivity. The 6 pi-electron electrocyclic ring closure appears to be reversible, and a preferred rotation of the alkenyl group, one of the three 2 pi-components, during the ring closure step provides the thermodynamically favored diastereomer as the major product.
Sklenicka
HM
Department of Chemistry, University of Minnesota, Minneapolis 55455, USA.
Hsung
RP
Wei
LL
McLaughlin
MJ
Gerasyuto
AI
Degen
SJ