α,ω-Diphenylpolyenes and Related Compounds

Abstract

Representatives of this series, up to n = 8, have been synthesized by Kuhn and Winterstein long ago (269). In each set they obtained the same end product, even when ten different routes had been followed. Although the all-trans configuration had been proved by X-ray studies for the samples n = 3 and 4 [Hengstenberg and Kuhn (160)], the existence of cis forms was predicted by Kuhn and Winterstein (270) (p. 8). In 1939 Cook and Jones wrote (71):

“…the behaviour of diphenyl-hexatriene and -octatetraene on a chromatographic column after irradiation in benzene-petroleum ether solution…indicates the formation of labile (cis-) isomerides.”