Synthesis and properties of methanothia-[15]-, -[17]-, -[19]-, -[21]-, -[23]-, -[25]-, -[27]-, -[29]-annulene and dimethanodithia-[26]- and -[30]-annulene

Abstract

ChemInform Abstract Title compounds such as (III) and (IV) are prepared via double Wittig reaction of the dicarbaldehydes (I). Some of these polyenes exist as sole isomers; the geometries of the double bonds can be determined by NMR. In other cases E,Z-mixtures are obtained. The 1H NMR spectra show that the methanothia-(17)-, -(19)-, -(23)-, and -(27)-annulenes sustain ring current, while the remaining title compounds do not. Dynamic NMR analysis of the methylene protons reveals the flipping of the methylene bridge above and below the average plane of the macrocycle.

Synthesis and Relative Diatropicity of a Remarkably Aromatic Thia[13]annulene

“…In Kato's annulene 5 , the annulene form is stable, but diatropicity conclusions based on coupling constant data suggested the compound had little aromaticity. Sondheimer's thia[13]annulene 6 , and Ojima's series 7 ( n = 2−4) and 8 ( n = 2−4, m = n + 1) appear to be diatropic, though not strongly. In these cases, despite their elegant syntheses, it is difficult to calibrate the aromaticity because of anisotropy effects, conformational mobility, or just plain lack of a good comparison parent annulene, particularly one with the same geometry.…”

Synthesis, conformation and tropicity of dimethano-bridged tetradehydrothia[21]-, -[23]- and -[25]annulenes

“…(1 H, d, J 14) and 2.037 (1 H, d, J 12.7): 6,(75.47 MHz) 133.96 (t), 132.92 (t), 132.67 (t), 132.52 (t), 131.44 (q), 131.18 (q), 130.19 (t), 130.14 (t), 129.72 (t), 129.62 (t), 127.67 (t), 127.64 (t), 127.53(t), 126.1 1 (t), 125.57 109.41 (q), 84.34 (4, -G), 83.69 (4, -G), 71.59 (9, -Cz), 71.22(t), 124.69(t), 113.87 (q), 113.76(9). 85.80 (q, -G ) , 85.01(9, …”