Synthesis of Tetracyclo[6.2.2.2^3,6.0^2,7]tetradeca‐4,9,11,13‐Tetraene

Abstract

The title hydrocarbon 3, a C 14H14 tetracyclic tetracne of C 2v-symmetry, was synthesized by new routes starting from 1,8,9,1O-tetrachloro-ll,1l-dimethoxytricyclo[6.2.1.0Z,7]undeca-3,5,9-triene (I). The DielsAlder cycloaddition of 1 with 2-chloroacrylyl chloride, a ketene equivalent, followed by subsequent reduction, dechlorination and deacctalization afforded the ketal 12 as a key intermediate. Elaboration of target compound 3 was carried out by either the method of ring enlargement of 12 or (better) the route of DielsAlder reaction of decarbonylated 12 with trans-l,2-bis(phenylsulfonyl)ethenc, an acetylene equivalent, to give trienol17, followed by dehydration. Upon irradiation, 3 underwent intercyclic [2+2J-addition to caged hexacyclic diene 4. At 120°C, 3 decomposed into barrelene and benzene quantitatively.

Photochemistry of Cyclobutanes: Synthesis and Reactivity

“…Analogously, the tetraene 442b undergoes photochemical cage formation yielding 444 281 . Other cyclizations are also of interest, such as the formation of the cage compound 445 (90%) from direct irradiation of a benzene solution of the diene 446 282 .…”