The chemical study of pseudoaromatic compounds. IV The electronic structure of tropothione

Synthesis and Some Reactions of 2,4,6‐Cycloheptatrienethione

“…The other two multiplets at 6.4-6.6 and at 6.6-6.S ppm were assigned to the remaining four ring protons. Although these values must be regarded with caution since the substance was never isolated, they support the conclusion of Machigwhi et al [4] based on a molecular orbital calculation that tropothione shows polyolefinic character and that dipolar contributions to the overall resonance structure similar to those proposed for tropone [12] are small. Under similar conditions tropone gives a single broad signal in the 1H-NMR.…”

“…These results are in good agreement with the UV. spectrum first reported by Kituhura [6] (noted above) but does not agree with the spectrum published recently by Machipihi [4]. The latter spectrum in methanol contains an additional maximum at A = 316 nm which may in fact be due to the presence of some tropone in the sample.…”

“…The tropothione dissolved in the sulfuric acid and the carbon tetrachloride separated as a layer on the top. (4). A solution of 2.96 mniol of tropothione, 42% yield, wcre prepared as described above from 0.746 g (7.05 mmol) of tropone and 2.982 g (13.4 mmol) of phosphorus pentasulfide.…”

“…Recent publications on the cycloaddition of cycloheptatrienethione (1) (tropothione) with dienophiles [l], its reaction with dichloroketene and with tetracyanoethylene [Z], its reaction with diazomethane [3] and a study of the electronic structure of 1 [4] have prompted this report on work carried out some time ago on the synthesis and some reactions of 1.…”