DIMETHYL A[CD]PENTALENE-8B-CARBOXYLATE-8C-THIONOCARBOXYLATE AND THE CORRESPONDING 8C-THIOLOCARBOXYLATE

The title compounds, methyl thoxy(thiocarbonyl)]-4b,8b,8c,8d-tetrahydr odibenzo [a,f]cyclo-propa [cd] pentalene-8b-carboxylate, C20H16O3S, an d methyl methylthio)]carbonyl-4b,8b,8c,8d-tetrahydrodibenzo [a,f]cyclo propa[cd]pentalene-8b-carboxylate, C20H16O3S, are the photoproducts in the photolysis of the dibenzobarrelene thiono and thiolo esters, The geometry and dimensions of the molecules are similar to those of relat ed materials. Only one photoproduct (of two possible) is formed in eac h case, with initial vinyl-benzo bond formation involving the vinyl C atom carrying the non-thioester group; intermediate biradicals are sta bilized by resonance interaction with the thioester groups.