1,3,12,14-Tetramethyldibenzo[a,i]dithieno[3,4-e;3′,4′-m]cyclohexadecene. Reactions of the bis-ylide from 2,5-dimethylthiophen-3,4-diylbis(methylenetriphenylphosphonium chloride) with 2,5-dimethylthiophen-3,4-dicarbaldehyde and with o-phthalaldehyde

Abstract

Reaction of the bis-ylide derived from 2,5-dimethylthiophen-3,4-diylbis(methylenetriphenylphosphonium chloride) with 2,5-dimethylthiophen-3,4-dicarbaldehyde gave cis,cis-, cis,trans- and trans,trans-2,5-dimethyl-3,4-bis-[2-(2,4,5-trimethyl-3-thienyl)vinyl]thiophen [as (IV)]. With o-phthalaldehyde a similar mixture of isomers was formed, but in addition the macrocycle 1,3,12,14-tetramethyldibenzo[a,i]dithieno[3,4-e;3′,4′-m] cyclohexadecene [as (V)] was obtained as a mixture of geometrical isomers. The n.m.r. spectrum of this substance gave no evidence of a ring current.