SILVER-CATALYZED 1,2-ACYL MIGRATION IN AN OPTICALLY-ACTIVE CHLOROHYDRIN - EVIDENCE FOR NEIGHBORING-GROUP PARTICIPATION BY CARBONYL CARBON

Molecular rearrangements where the migrating substituent stabilizes the transition state by becoming bonded to an adjacent reaction center in the rate-limiting step is by definition a concerted process. A classic example of such neighboringgroup participation (NGP)1 is the phenonium ion which was introduced by Cram in his studies on stereospecific tosylate solvolyses.2 The substrates used in these experiments usually required assistance by the migrating phenyl group to effect ionization of the leaving group and the results were best explained by a bridged-ion intermediate. © 1979, American Chemical Society. All rights reserved.