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Title annulenes were synthesized by Wittig reaction of cyclohepta-1,3,5-triene-1,6-dialdehyde or its vinylogous dialdehydes with 5-methylpenten-2-yn-4-yltriphenylphosphonium bromide, followed by intramolecular oxidative couplings of the resulting acyclic compounds, and they proved to be diatropic or paratropic, corresponding to the number of peripheral π-electrons.

The title annulenes (4a–d) have been synthesized by a Wittig reaction of cyclohepta-1,3,5-triene-1,6-dicarbaldehyde (1a) or its vinylogous dialdehydes (1b–d) with 3-methylpent-2-en-4-ynyltriphenylphosphonium bromide (2), followed by intramolecular oxidative coupling of the resulting acyclic compounds. They proved to be diatropic or paratropic, depending on the number of peripheral π-electrons. The related [1,3]cyclophanpolyenediynes (11), (14), (17), (19), (21), and (23) were prepared by a double Wittig reaction of 3-methylpent-2-en-4-ynal (8) and/or its vinylogous aldehydes (9) and (10), with 1,3-bis(triphenylphosphoniomethyl)benzene dibromide (7), followed by intramolecular oxidative coupling of the resulting acyclic compounds. Their properties are compared, on the basis of 1H n.m.r. and electronic spectral results, with those of tetradehydromethanoannulenes.

Title annulenes (21)–(28) have been synthesized by a Wittig reaction of 1,6-bis-(4-formylbuta-1,3-dienyl)cyclohepta-1,3,5-triene (5) and the vinylogous dicarbaldehydes (6)–(10) with 3-methylpent2-en-4-ynyl(triphenyl)phosphonium bromide (11) or triphenyl-(3-t-butylpent-2-en-4-ynyl)phosphonium bromide (12), followed by intramolecular oxidative coupling of the resulting acyclic diacetylenes, and their properties are discussed on the basis of 1H n.m.r. and electronic spectra.

The title aza[12]annulene has been synthesized by Beckmann rearrangement of the oxime from the methano[11]annulenone, followed by alkylation of the resulting lactam. Examination of the 1H NMR spectrum indicates that the aza[12]annulene is slightly paratropic.

The title annulenes (4a–d) have been synthesized by a Wittig reaction of cyclohepta-1,3,5-triene-1,6-dicarbaldehyde (1a) or its vinylogous dialdehydes (1b–d) with 3-methylpent-2-en-4-ynyltriphenylphosphonium bromide (2), followed by intramolecular oxidative coupling of the resulting acyclic compounds. They proved to be diatropic or paratropic, depending on the number of peripheral π-electrons. The related [1,3]cyclophanpolyenediynes (11), (14), (17), (19), (21), and (23) were prepared by a double Wittig reaction of 3-methylpent-2-en-4-ynal (8) and/or its vinylogous aldehydes (9) and (10), with 1,3-bis(triphenylphosphoniomethyl)benzene dibromide (7), followed by intramolecular oxidative coupling of the resulting acyclic compounds. Their properties are compared, on the basis of 1H n.m.r. and electronic spectral results, with those of tetradehydromethanoannulenes.

Title annulenes (21)-(28) have been synthesized by a Wittig reaction of 1,6-bis-(4-formylbuta-1,3-dienyl)cyclohepta-1,3,5-triene (5) and the vinylogous dicarbaldehydes (6)-(10) with 3-methylpent-2-en-4-ynyl(triphenyl)phosphonium bromide (11) or triphenyl-(3-t-butylpent-2-en-4-ynyl)phosphonium bromide (12), followed by intramolecular oxidative coupling of the resulting acyclic diacetylenes, and their properties are discussed on the basis of 1H n.m.r. and electronic spectra.