4-Acetoxyazetidin-2-one (6) has been converted into (E)- and (Z)-1-[azido(t-butoxycarbonyl)methyl]-[2-(ethoxycarbonyl)vinylthio]azetidin-2-one (10) and (13). Thermolysis of either geometrical isomer in refluxing xylene afforded t-butyl (2RS,6RS)-4-ethoxycarbonylmethyl-8-oxo-5-thia-1,3-diaza-bicyclo[4.2.0]oct-3-ene-2-carboxylate (17) and both C-2 epimers of 5-ethoxycarbonyl-9-oxo-6-thia-1,3-diazabicyclo[5
4-乙酰氧基氮杂
环丁烷-2-酮(6)已被转化为(E)-和(Z)-1- [
叠氮基(叔丁氧基羰基)甲基]-[2-(乙氧基羰基)
乙烯基硫基]氮杂
环丁烷-2-酮(10)和(13)。任一几何异构体在回流的二
甲苯中热解,得到叔丁基(2 RS,6 RS)-4-乙氧基羰基甲基-8-氧代-5-
硫杂-1,3-二氮杂-双环[4.2.0]辛-3-烯- 2-
羧酸盐(17)和5-乙氧基羰基-9-氧代-6-
硫杂-1,3-二
氮杂双环[5.2.0]非-4-烯-2-
羧酸盐的两个C-2差向异构体(14)和(15)。