During our study of MCPs, we have found CuX 2 -mediated cyclization reaction of cyclopropylideneacetic acids and esters to give 4-substitued-2-(5H)furanones and 3,4-substituted-5,6-dihydro-2H-pyran -2-ones under mild conditions. [5] This interesting result stimulated us to further investigate the CuX 2 -mediated reactions of alkylidenecyclopropanes. Herein we wish to report the ring-opening reactions of MCPs 1 promoted by copper halides under mild conditions in which (Z)-2,4- ...
