General Synthesis, Spectroscopic Properties, and Dipole Moments of 2-Substituted Tropothiones
作者:Takahisa Machiguchi、Toshio Hasegawa、Yuichi Kano
DOI:10.1246/bcsj.66.3699
日期:1993.12
Several 2-substituted tropothiones (2,4,6-cycloheptatriene-1-thiones) having an electron-donating group (Me, Ph, NH2, NHMe, OH, OMe, or SMe) were synthesized by direct sulfurization from the corresponding tropones in a one-pot reaction. In contrast to the instability of the parent tropothione (1a), most of these 2-substituted derivatives were insensitive to air and were thermally stable compounds which can be handled at room temperature. These tropothione derivatives were characterized by spectroscopic and dipole moment measurements. The IR spectra showed ν(C=S) vibrations at around 1100—1040 cm−1. The UV-vis spectra displayed three π–π* transitions accompanied by n–π* transitions. The 400-MHz 1H NMR spectra of the thiones showed that only protons at the 7 position resonate well-separated downfield from the other ring protons due to the strong C=S anisotropy. In the 13C NMR (100.6 MHz) spectra, the C=S carbon signals appeared at < δ = 183 and the other ring carbons resonated at δ = 154—112. Variable-temperature 13C as well as 14N NMR spectroscopic studies clarified that 2-amino- and 2-(methylamino)tropothiones exist as an equilibrium mixture of the thione and enethiol structures in an approximate ratio of 64 : 36. This is different from the results of a previous investigation showing that the structures exist as the thione form exclusively. Dipole moments of some derivatives of 1a were measured and compared with those of the corresponding tropones. These tropothione derivatives obtained were more ionic than both the parent compound 1a and the corresponding tropones.
几种具有电子给体基团(如甲基、苯基、氨基、甲氨基、羟基、甲氧基或硫甲基)的2-取代类萜烯硫酮(2,4,6-环七烯-1-硫酮)通过从相应的类萜酮直接硫化反应合成,采用一锅法。在与不稳定的母体类萜烯硫酮(1a)相比,这些大多数2-取代衍生物对空气不敏感,并且是热稳定化合物,可以在室温下处理。这些类萜烯硫酮衍生物通过光谱和偶极矩测量进行了表征。红外光谱显示在约1100—1040 cm−1处有ν(C=S)的振动。紫外-可见光谱显示伴随n–π*跃迁的三个π–π*跃迁。400-MHz的1H NMR光谱显示,仅有7位的质子因强C=S各向异性而与其他环上的质子分开共振。13C NMR(100.6 MHz)光谱中,C=S碳信号出现在< δ = 183,其他环碳的共振在δ = 154—112。变温13C和14N NMR光谱研究表明,2-氨基和2-(甲氨基)类萜烯硫酮以大约64 : 36的比例存在于硫酮与烯硫醇结构的平衡混合物中。这与之前的研究结果不同,后者表明这些结构仅存在于硫酮形态。对一些1a衍生物的偶极矩进行了测量,并与相应类萜酮的偶极矩进行了比较。这些获得的类萜烯硫酮衍生物比母体化合物1a和相应类萜酮更具离子性。