An efficient synthesis of (Z)-γ-fluoroallylphosphonates using a base-promoted deconjugation of (E)-γ-fluorovinylphosphonates, and its utility as fluoroolefin-containing building block
作者:Gerald B. Hammond、Daniel J. deMendonca
DOI:10.1016/s0022-1139(99)00244-4
日期:2000.3
A three-step synthesis of γ-fluoroallylphosphonates starting with α,β-unsaturated aldehydes is described. Treatment with diethyl phosphite in the presence of KF gives α-hydroxyallyl phosphonate in excellent yield; DAST deoxofluorination produces the corresponding γ-fluorovinylphosphonate through a SN2′ mechanism, and finally, a base-promoted double bond migration leads to the desired γ-fluoroallylphosphonate
描述了一种以α,β-不饱和醛为原料的γ-氟代烯丙基膦酸酯的三步合成法。在KF存在下用亚磷酸二乙酯处理得到α-羟基烯丙基膦酸酯,收率极好。DAST脱氧氟化通过S N 2'机制产生相应的γ-氟乙烯基膦酸酯,最后,碱促进的双键迁移导致所需的γ-氟代烯丙基膦酸酯。γ-氟代烯丙基膦酸酯是合成氟烯烃的有用组成部分。一项探索性研究得出了(Z)-二乙基1-苄基-3-氟-2-丁烯基膦酸酯和(Z)-二乙基1,3-二氟-2-己烯基膦酸酯的优异产率。LiN(TMS)2处理(E)3-氟-2-己烯基膦酸二乙酯和苯甲醛在THF导致优先形成的顺式- (ż) -二乙基-3-氟-1-(羟基苄基)-2- butenylphosphonate。