Generation and in situ Diels-Alder Reactions of Activated Nitroethylene Derivatives.

Abstract Dienes readily undergo Diels–Alder reaction with CH 2 C(NO 2 )SO 2 Ph ( 2a ), CH 2 C(NO 2 )CO 2 Et ( 2b ), and CH 2 C(NO 2 )COPh ( 2c ), all observed in situ by 1 H NMR. The cycloadducts of 2a undergo S RN 1 reactions.