Syntheses and properties of dicyanodimethyltetradehydro-trideca-, -pentadeca-, -heptadeca-, and -nonadeca-annulenes, and benzannelated tridecafulvene derivatives

Abstract

Syntheses of (5,10-dimethylcyclotrideca-2,4,10,12-tetraene-6,8-diynylidene)-(5), (7,12-dimethylcyclopentadeca-2,4,6,12,14-pentaene-8,10-diynylidene)-(6), (7,12-dimethylcycloheptadeca-2,4,6,12,14,16-hexaene-8,10-diynylidene)-(7), and (9,14-dimethylcyclononadeca-2,4,6,8,14,16,18heptaene-10,12-diynylidene)-malononitrile (8) are described. Examination of the ¹H n.m.r. spectra indicates that both compounds (5) and (7) are paratropic, while both (6) and (8) are diatropic. Syntheses of benzannelated derivatives of compound (5), i.e.(11-methyl-12,13,14,15-tetrahydro-7H-benzocyclotridecen-7-ylidene)(9), and (14,15,16,17-tetradehydrodibenzo[a,g]cyclotridecen-7-ylidene)-malononitrile (10) are also described. The influence of the dicyano substitution at the exocyclic bond of these annulenes, and of benzannelation upon the tropicity of the dicyanotetradehydro[13]annulene, is discussed on the basis of the ¹H n.m.r. and u.v. spectra of these compounds.