Alkyl thiobenzimidates in which the nitrogen atom is derived from the methyl ester of glycine (7), DL-valine (8), or didehydrovaline [(14) and (19)] undergo cycloaddition with diphenylketen to give the respective N-substituted 4-alkylthio-3,3,4-triphenylazetidin-2-ones (20)–(23). The methyl thiobenzimidate derivative (14) of didehydrovaline was conveniently prepared by ring cleavage of methyl 5,5-
其中氮原子衍生自甘
氨酸(7),
DL-缬氨酸(8)或二氢缬
氨酸[(14)和(19)]的甲基的烷基
硫代苯并
甲酸酯与二苯基酮进行环加成反应,得到各自的N-取代的4-烷
硫基3,3,4-三苯基氮杂
环丁烷-2-酮(20)–(23)。didehydrovaline的甲基thiobenzimidate衍
生物(14)中的溶液方便地通过甲基的环裂解而制得5,5-二甲基-2-苯基- Δ 2
噻唑啉-4-
羧酸甲酯(16),随后小号中间thioenolate离子的烷基化(13 )。通过与(14)的交换反应获得2-甲氧基羰基乙基
硫代
苯并咪唑酸酯(19)。
噻唑啉酯的互变(16)和4-异丙基-2-苯基- Δ 2-
噻唑啉-5-酮(12)和碱诱导的4-(2-甲氧基羰基-乙
硫基)-1-(1-甲氧基羰基-2-甲基丙-1-烯基)-3,3,4-三苯基氮杂
环丁烷-的降解描述了2-一(23)。