[3+2]-cycloaddition reactions of 2-phenyliodonio-1,3-dioxacyclohexanemethylide: Facile synthesis of fused dihydrofuran derivatives

Iodonium ylide 2, derived from 1,3-cyclohexadione, undergoes thermal [3+2]-cycloaddition with acetonirile, carbon disulfide and p, P'- dimethoxythiobenzophenone with Cu(acac)(2) catalysis to form the corresponding 5-membered heterocycles and alkene respectively. Photochemically 2 reacts with various alkenes and dienes to form dihydrofuran derivatives, key intermediates for paniculide A, B and pentalene synthesis. (C) 1998 Elsevier Science Ltd. All rights reserved.