Abstract Pyridinium salts Py+-CH 2-EWG (EWG= CO 2 Et, CONEt 2, CN, COMe, COPh) reacted with Michael acceptors Ar-CH= C (CO 2 Et)(Acc)(Acc= CO 2 Et, COMe, SO 2 Me, CONH 2) at ambient temperature in the presence of base to give [3+ 2]-cycloadducts by stepwise [3+ 2]-cycloaddition of the intermediate pyridinium ylides. Treatment of the crude reaction mixtures with 1 equiv. of chloranil and atmospheric oxygen in the presence of ...
