3-(2-alkenoyl)-thiocarbazic acid O-methyl esters 1 are desulfurated by bromine and the unknown intermediates are transformed by alkali to 5-(1-alkenyl)-1, 3, 4-oxadiazol-2(3H)-ones (2). This type of oxadiazolone substitution is not realizable by the common ring closure of hydrazides with phosgene due to pyrazolidinone ring closure of unsaturated acids with hydrazine.
3-(2-链烯酰基)-
硫代
氨基甲酸O-甲酯1被
溴脱
硫,未知的中间体被碱转化为5-(1-链烯基)-1,3,4-恶二唑-2(3 H)-一个(2)。这种类型的
恶二唑酮取代不能通过酰
肼与
光气的常见闭环实现,这是由于不饱和酸与
肼的
吡唑烷酮闭环。