An Unusual Oligimerization/Oxidation Reaction of a 3-Boron-Substituted 1-Phenyl-1,3- Butadiene Produces a Hexameric Product

Butadiene Produces a Hexameric Product. Subhasis De, Cynthia S. Day, and Mark E. Welker* Department of Chemistry, Wake Forest University, P.O. Box 7486, Winston-Salem, NC 27109 An unusual hexameric structure has been isolated from exposure of 3-BF3-1-Phenyl-1,3Butadiene to air and moisture in an attempt to obtain crystals of the starting compound. Formation of this hexamer is rationalized and its structural features are compared to other B(OR)2 substituted cyclohexane and benzene ring containing structures. Comment We have recently begun to prepare 2-boron(De and Welker, 2005) and 2-silicon-substituted 1,3-dienes and investigate their Diels-Alder/Cross coupling reactions (Pidaparthi, Day, and Welker, 2007). Most recently, we reported the preparation of several halogen substituted phenylbutadienes and their conversion into boron substituted dienes (De, Day, and Welker, 2007). To our surprise, when we attempted to grow crystals of BF3 substituted diene (I) in ethyl acetate under atmospheric conditions we isolated a symmetrical structure (II) derived from 6 molecules of (I).