Reaction of 2-Quinolyl Thiocyanate with C-Nucleophiles.
作者:Chihoko IIJIMA、Emiko HIYOSHI、Akira MIYASHITA
DOI:10.1248/cpb.40.1090
日期:——
2-Quinolyl thiocyanate (2) was found to react with C-nucleophiles, i.e., phenylacetonitrile, p-chlorophenylacetonitrile, p-cyanophenylacetonitrile, p-methoxyphenylacetonitrile, ethyl cyanoacetate, and malononitrile, in two ways, depending on the nature of the reagent. The more reactive phenylacetonitrile carbanions attacked at the less reactive sulfur atom, which is less subject to steric effect compared with the 2-position carbon of 2, to give the corresponding sulfides (α-(2-quinolylthio)phenyl- (8), α-(2-quinolylthio)-4-chlorophenyl- (9), α-(2-quinolylthio)-4-cyanophenyl- (10), and α-(2-quinolylthio)-4-methoxyphenylacetonitrile (11)). The less reactive ethyl cyanoacetate and malononitrile carbanions attacked at the more reactive 2-position carbon of 2 to afford the corresponding ipso-substitution products (α-cyano-2-quinolineacetate (4) and 2-quinolinemalononitrile (7)). However, in the reaction of diethyl malonate carbanion, diethyl 2-quinolinemalonate (12) was not obtained, presumably for steric reasons.
研究发现,2-喹啉基硫氰酸盐(2)与 C-亲核物(即苯乙腈、对氯苯乙腈、对氰基苯乙腈、对甲氧基苯乙腈、氰乙酸乙酯和丙二腈)发生反应的方式有两种,这取决于试剂的性质。反应活性较高的苯乙腈碳离子会攻击反应活性较低的硫原子,因为与 2 的 2 位碳相比,硫原子受立体效应的影响较小、得到相应的硫化物(α-(2-喹基硫基)苯基-(8)、α-(2-喹基硫基)-4-氯苯基-(9)、α-(2-喹基硫基)-4-氰基苯基-(10)和 α-(2-喹基硫基)-4-甲氧基苯基乙腈(11))。反应活性较低的氰基乙酸乙酯和丙二腈碳离子攻击反应活性较高的 2 的 2 位碳,生成相应的同位取代产物(α-氰基-2-喹啉乙酸酯(4)和 2-喹啉丙二腈(7))。然而,在丙二酸二乙酯碳酰离子反应中,可能由于立体原因,没有得到 2-喹啉丙二酸二乙酯(12)。