Exploring the Steric and Electronic Factors Governing the Regio- and Enantioselectivity of the Pd-Catalyzed Decarboxylative Generation and Allylation of 2-Azaallyl Anions.

Abstract

The impact of the steric and electronic factors in both the para-substituted benzaldimine and 2,2-diarylglycine components on the regioselectivity and enantioselectivity of the palladium-catalyzed decarboxylative allylation of allyl 2,2-diarylglycinate aryl imines was explored. These studies revealed that using 2,2-di(2-methoxyphenyl)glycine as the amino acid linchpin allowed for the exclusive synthesis of the desired homoallylic benzophenone imine regioisomers, independent of the nature of the imine moiety, in typically high yields. The resulting enantiomeric ratios, however, are slightly decreased in comparison to the transformations involving the corresponding allyl 2,2-diphenylglycinate imines, but this is more than balanced out by the increases in yield and regioselectivity. Overall, these studies suggest a general strategy for the highly regioselective functionalization of 2-azaallyl anions.