Kazuyo Wada

Trimethylbisdehydro[23]- and -[25]annulenones

Abstract Syntheses of trimethylbisdehydro [23]- and -[25]annulenones have been described, and the examination of their 1 H NMR spectra suggests the diatropicity and the paratropicity of the 25-membered and 25-membered rings, respectively.

Syntheses and properties of a trimethyltetradehydro[23]annulenone and a trimethyltetradehydro[25]annulenone

The syntheses of 2,9,14-trimethyl-10,11,12,13-tetradehydrocyclotricosenone (6) and 2,11,16-trimethyl-12,13,14,15-tetradehydrocyclopentacosenone (7) are described. Examination of the 1H n.m.r. spectra indicates that (6) is diatropic, whereas (7) is paratropic, and these ring currents are increased by dissolution in deuteriotrifluoroacetic acid.

Syntheses and properties of trimethyltetradehydro[15]annulenones and the benzannelated derivatives

Syntheses of 5,10,15-(8) and 2,5,10-trimethyl-6,7,8,9-tetradehydrocyclopentadecenone (12), and 8,13-(9) and 6,13-dimethyl-14,15,16,17-tetradehydrobenzocyclopentadecen-7-one (13), 8,13-(10) and 10,13-dimethyl-14,15,16,17-tetradehydrobenzocyclopentadecen-9-one (14), and 8-methyl-(11) and 6-methyl-16,17,18,19-tetradehydrodibenzo[a,g]cyclopentadecen-7-one (15) are described. The influence of α-methyl substitution and benzannelation upon the structure and tropicity of the tetradehydro[15]annulenone ring system is discussed in view of the 1H n.m.r. and u.v. spectra of these annulenones, as well as those of the α-methyl unsubstituted annulenones (4)–(7).

Syntheses and properties of a trimethyltetradehydro[21]annulenone and its benzannulated derivatives

The syntheses of 2,9,14-trimethyl-10,11,12,13-tetradehydrocycloheneicosenone (3), 19-methyl-20,21,22,23-tetradehydrobenzocycloheneicosen-11-one (4), and 10-methyl-22,23,24,25-tetradehydredibenzo[a,g]cycloheneicosen-11-one (5) are described. The influence of α-methyl substitution and benzannulatien on the structure and tropicity of the tetradehydro[21]annulenone ring system is discussed in view of the 1H n.m.r, and u.v. spectra of these annulenones, as well as those of the dimethylannulenone (2).

Synthesis and properties of a trimethyltetradehydro[17]annulenone and its benzannelated derivatives

Syntheses of 2,7,12-trimethyl-8,9,10,11-tetradehydrocycloheptadecenone (5), 10,15-(6) and 8,15-dimethyl-16,17,18,19-tetradehydrobenzocycloheptadecen-9-one (7), and 8-methyl-18,19,20,21-tetradehydrodibenzo[a,g]cycloheptadecen-9-one (8) are described. The 1H n.m.r. spectra of these annulenones and related compounds indicate that the skeleton of the tetradehydro[17]annulenone ring system is more planar and less strained than that of the corresponding [13]annulenones.