2,2'-BISALLYLMETHANE - THERMAL DEGENERATE REARRANGEMENT OF 1,3-DIMETHYLENECYCLOPENTANE - PARTLY STEREOSPECIFIC CLOSURE OF A BIRADICAL

The 2, 2'-bisallylmethane diradical (2, 2'-BAM) appears to be generated as an intermediate upon thermolysis of 1, 3-dimethylenecyclopentane (DMCP).1 This conclusion derives from the finding that formal [1, 3]- and [3, 3]-shift products are formed in a 2:1 ratio, respectively.1 However, pyrolysis of cis- and of trans-4, 5-dimethyl-DMCP leads to stereoisomeric products from each in a manner that indicates partial stereospecificity in the formation of the biradical.1 This communication reports stereospecificity in the closure of the biradical to the [1, 3]-shift product with partial inversion of configuration of the migrating carbon. In addition, different rate- and product-determining deuterium isotope effects further substantiate the intervention of an intermediate. © 1979, American Chemical Society. All rights reserved.