| Abstract
| - The unsubstituted 1,2,5-trithiepin (1) has beensynthesized from the known 1,2,5-trithiepane(6)through two consecutive Pummerer rearrangements. Proton and carbonNMR spectra werecompletely analyzed, assigned, and correlated. The protons in1 are shifted downfield by Δδ =0.57 ppm for H3/H7 (δ = 6.57 ppm) and by1.10 ppm for H4/H6 (δ = 7.24 ppm) relativeto the 6,7-dihydro-1,2,5-trithiepin (7). These downfield shifts arecomparable to thiophene, thus characterizing1,2,5-trithiepin (1) as the first multisulfur 10π-aromaticdiatropic molecule incorporating a disulfidelinkage. 6,7-Dihydro-1,2,5-trithiepin (7) is a dynamicsystem. Variable-temperature 1H-NMRmeasurements of 7 yielded an estimated free energy ofactivation at the coalescence temperature(227 K) of ΔG⧧ = 9.83kcal/mol.
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