The Chemistry of Novel[7]Annulene Compounds

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We have found the following results,1.The absorption bands of tropothione are assigned by a new method "magnetic circular-dichroism".2.[7]Annulenthione, which is valence isoelectronic with tropone, reacts concertedly with fulvene to give 1 : 1[8 + 2]cycloadducts. The product configuration is sharply different from that of the initially formed[6 + 4]cycloadduct between tropone and fulvene. The reaction mechanism are studies kinetically and by molecular orbital calculations. The obtained endo form of the[8 + 2]product is found to arise from the secondary orbital interaction in the course of the intrinsic reaction coordinate.3.Thermally stable[7]annulenthiones have been synthesized by direct thiocarbonylation of the corresponding tropones in polar solvents. The products are characterized by IR, UV-visible, and ^1H, ^<13>C, ^<14>N NMR spectroscopies.4.The reaction of 8, 8-dicyanoheptafulvene and cyclopentadienide anion affords under mild condition two unusual tetracyclic cage molecules. The structures are elucidated using various modern NMR spectroscopic techniques and deuterium-labeling experiments. The easy formation of the considerably strained molecules is ascribed to a nucleophilic addition, followed by protonation and an intramolecular Diels-Alder reaction with normal electron demand. MNDO-MO calculations suggest a possible mechanism.5.[7]Annulenthione S-oxide have been synthesized as stable dark red needles (mp 68ﾟC)in high yield. The structure and chemical behaviors of the sulfur are investigated both by X-ray analysis and ^<13>C, ^<17>O, ^<33>S NMR spectroscopies and this compound is found to be the first exmaple of a sulfine charge reversion(umpoulung).2-Amino[7]annulenimine is conveniently synthesized in high yield and is isolated in pure form.