The synthesis of the monomethyl isomers of benzo[b]naphth[2,1-d]thiophene

All isomers of the monomethylbenzob]naphth2,1-d]thiophenes were synthesized using photocyclization of 3-styrylbenzob]thiophenes. The 1-, 3-, 4-, and 5-methylbenzob]naphtho2,1-d]thiophenes were synthesized by irradiation of the corresponding methylated 3-styrylbenzob]thiophenes which were prepared by the Wadsworth-Emmons reaction of diethyl benzob]thenylphosphonate with o-, m-, p-tolualdehyde and acetophenone. The 7-, 8-, 9- and 10-methylbenzob]naphtho2,1-d]thiophenes were synthesized by decarboxylation of 7-, 8-, 9- and 10-methylbenzob]naphtho2,1-d]thiophene-6-carboxylic acid with copper in quinoline. These carboxylic acids were prepared by photocyclization of the corresponding 2-(benzob]thiophen-3-yl)-3-phenylpropenoic acids which were prepared by the condensation of the methylated benzob]thiophene-3-ylacetic acids with benzaldehyde in the presence of triethylamine in acetic anhydride.