N-Phenyl-N-(trifluoromethylsulfonyl)propiolamides react with triphenylphosphane in the presence of various active methylene compounds CH2XY in a 1:1:1 molar ratio to furnish 1-phosphonium-5-oxabetaines, Ph3P+–C(R)=CH–C(O–)=CXY. These betaines are formed preferentially, but not exclusively, as E-diastereoisomers with respect to the vinylic double bond. In some cases, separation of the two diastereoisomers
N-苯基-N-(三
氟甲基磺酰基)丙酰胺与
三苯基膦在各种活性亚甲基化合物CH 2 XY的存在下以1:1:1的摩尔比反应,生成1- 1--5-氧杂
甜菜碱,Ph 3 P + –C( R)= CH–C(O –)= CXY。这些
甜菜碱相对于
乙烯基双键优选但不排他地形成为E-非对映异构体。在某些情况下,通过分级结晶可实现两种非对映异构体的分离。通过X射线衍射分析确定结构,发现E和Z的CH–C(O –)单键周围明显的构象差异-异构体和阴离子部分中扩展的电荷离域。