[3+2]-cycloaddition reactions of 2-phenyliodonio-5,5-dimethyl-1,3-dioxacyclohexanemethylide

Iodonium ylide 2, derived from dimedone, undergoes thermal [3+2]-cycloaddition with acetylenes and nitriles with Rh-2(OAc)(4) to form the corresponding furans and oxazoles, respectively. Photochemically 2 reacts with various alkenes to form E-dihydrofuran derivatives. (C) 2000 Elsevier Science Ltd. All rights reserved.