Abnormal Diels-Alder Reaction of 5-Alkoxythiazoles with Highly Reactive Dienophiles; 4-Phenyl-3<i>H</i>-1,2,4-triazole-3,5(4<i>H</i>)-dione, Diethyl Azodicarboxylate, and Diethyl Oxomalonate
作者:Xiaolan Shi、Toshikazu Ibata、Hiroyuki Suga、Kiyoshi Matsumoto
DOI:10.1246/bcsj.65.3315
日期:1992.12
thiazole ring opening. Diethyl azodicarboxylate also gave 2,3-dihydro-1H-1,2,4-triazole derivatives in moderate yields. High pressure improved the yields a little. On the other hand, the reaction of diethyl oxomalonate in the presence of tin tetrachloride with 4-unsubstituted thiazoles did not give an adduct of similar type but gave diethyl 2-hydroxy-2-(4-thiazolyl)malonate through the usual electrophilic
5-烷氧基噻唑与等摩尔量的 4-苯基-3H-1,2,4-三唑-3,5(4H)-二酮 (PTAD) 在乙腈溶液中在室温下反应得到相应的 O-烷基 6, 7-dihydro-5,7-dioxo-6-phenyl-1H,5H-[1,2,4]triazolo[1,2-a] [1,2,4]triazole-1-carbothioate,收率很高。假设反应是通过向噻唑逐步添加 PTAD 并伴随噻唑开环来进行的。偶氮二羧酸二乙酯也以中等产率得到2,3-二氢-1H-1,2,4-三唑衍生物。高压稍微提高了产量。另一方面,在四氯化锡存在下,氧代丙二酸二乙酯与 4-未取代的噻唑的反应没有得到类似类型的加合物,而是通过通常的亲电取代反应得到 2-羟基-2-(4-噻唑基)丙二酸二乙酯C-4 位的噻唑。