Cycloaddition reactions of 1,3-dimethylallene. Assignment of stereochemistry of the cycloadducts and interpretation of product distributions

The structures of the cycloadducts formed in the (2+2) cycloaddition reactions of 1,3-dimethylallene (13DMA) with 1,1-dichloro-2,2-difluoroethene (1122), acrylonitrile (ACN), methyl acrylate (MAC), N-phenylmaleimide (NPMI), and diethyl fumarate (DEF) and maleate (DEM) and the product disitributions have been interpreted on the basis of favored conformations for diradical formation and ring closure to the cycloadducts