The synthesis and rearrangements of Hexamethylbicyclo[1,1,0]butane

Abstract

The synthesis of the title compound (1) by an intramolecular Wurtz reaction is reported. Acid-catalysed rearrangements of (1) gave isomeric products shown to be 2,3,4,5-tetramethylhexa- 1,4-diene (ll), 2,3,4,5-tetramethylhexa-2,4-diene (12) and 1-isopropenyl-1,2,2,3-tetramethylcyclopropane (13). Pyrolytic rearrangements in the vapour phase in the presence of triethylamine gave both (11) and (12). The production of (11) is most reasonably explained in terms of an initial non-concerted cleavage of the bicyclobutane to give a diradical species.