INVESTIGATION OF A MODEL FOR 1,2-ASYMMETRIC INDUCTION IN REACTIONS OF ALPHA-CARBALKOXY RADICALS - A STEREOCHEMICAL COMPARISON OF REACTIONS OF ALPHA-CARBALKOXY RADICALS AND ESTER ENOLATES

The stereochemical course of reductions and allylations of alpha-carbalkoxy radicals with chiral centers at the beta-position are reported. Radicals without polar substituents, with alkoxyl or acetoxyl groups, and with hydroxyl groups at the beta-position were examined. Reactions showed selectivities ranging from low (50:50) to high (99:1). The results are discussed in terms of transition-state models that emphasize the importance of (1) allylic conformational analysis (minimization of A1,3 and A1,2 strain), (2) torisonal strain (minimization of eclipsed interactions), and (3) stereoelectronic effects.