Nucleophilic vinylic substitutions of (Z)-(β-(phenylsulfonyl)-alkenyl)iodonium tetrafluoroborates with sodium benzenesulfinate: Stereoselective synthesis of (Z)-1,2-bis(phenylsulfonyl)alkenes
作者:Masahito Ochiai、Kunio Oshima、Yukio Masaki、Munetaka Kunishima、Shohei Tani
DOI:10.1016/s0040-4039(00)74100-1
日期:1993.7
Nucleophilicvinylicsubstitutions of (Z)-(β-(phenylsulfonyl)alkenyl)iodonium tetrafluoroborates with sodium benzenesulfinate afford (Z)-1,2-bis(phenylsulfonyl)alkenes with retention of stereochemistry in good yields.
The phenylsulfonyl group (PhSO2) has been examined for its beta effect properties. The stereochemical relationship was varied between phenylsulfonyl and a nucleophilic leaving group (nucleofuge) separated by two carbons. Mechanisms were distinguished through solvent effects on rates and products. When the stereochemistry between the two, groups was gauche, the only effect of phenylsulfonyl was strong inductive retardation in a mechanism involving solvent participation. With the antiperiplanar stereochemistry, however, the mechanism clearly changed to carbocation formation with a small kinetic acceleration. Thus, phenylsulfonyl is a weak beta effect substituent. This remarkable property for a strongly electron-withdrawing group occurs most likely through hyperconjugation or possibly through anchimeric assistance.
ASAKI, TETSUO;AOYAMA, TOYOHIKO;SHIOIRI, TAKAYUKI, HETEROCYCLES, 27,(1988) N, C. 343-346