The Pyrolysis of Butatrienone Precursors: 3,4-Diazatricyclo[5.2.1.0^2,6]deca-3,8-diene-endo-cis-2,6-dicarboxylic anhydride and Its 5,5-Diphenyl Derivative

Abstract

Flash vacuum pyrolysis of the title anhydride (4) gave a poor yield of butatrienone , detected by argon matrix isolation infrared spectroscopy. Similar pyrolysis of the 5,5-diphenyl derivative (8) failed to give diphenylbutatrienone ; the red product (16) is considered to have been formed by dimerization of an intermediate 2H-indenylidenemethanone (15). The crystal structure of (16) has been determined.