Conjugated tetraenes with both central double bonds of cis configuration undergo a series of thermal reactions, the observable products being markedly dependent on the nature of the terminal substituents. Dimethyl 2E, 4Z, 6Z, 8E-decatetraene-1, 10-dioate (16) was prepared and found to cyclize readily at 50° to trans dimethyl 2, 4-bicyclo [4.2. 0) octadiene- 6, 7-dicarboxylate (18). This reaction proceeds to equilibrium, and the rates and ...
