Synthesis of activated alkenes bearing the difluoromethylenephosphonate group: a range of building blocks for the synthesis of secondary difluorophosphonates
作者:Kevin Blades、Afshan H. Butt、G. Stuart Cockerill、Howard J. Easterfield、Thierry P. Lequeux、Jonathan M. Percy
DOI:10.1039/a907052d
日期:——
Active methylene compounds reacted readily with stable hydrate 2-diethoxyphosphoryl-2,2-difluoroethane-1,1-diol to afford a range of activated alkenes bearing the difluoromethylenephosphonate group, a useful motif in the synthesis of phosphate ester mimics of biological interest. Wadsworth–Horner–Emmons reactions were employed using modified Rathke conditions for the syntheses of alkenoates, an alkenoic acid and a vinyl sulfone, while a Henry reaction followed by E1cB dehydration afforded an enedioate and a nitroalkene. A vinyl sulfoxide was less straightforward to synthesise and dephosphorylation to a difluoromethyl congener accompanied attempts to force the reaction to completion.
活性亚甲基化合物与稳定的水合物2-二乙氧基磷酸酯-2,2-二氟乙烷-1,1-二醇反应,迅速生成一系列带有二氟亚甲基磷酸酯基团的活化烯烃,这是一种在合成生物学兴趣的磷酸酯类似物中有用的结构单元。采用改进的Rathke反应条件进行Wadsworth–Horner–Emmons反应,合成了烯酸酯、一种烯酸和一种乙烯基磺酮,而亨利反应后进行E1cB脱水则得到了一个环烯酸酯和一个硝基烯烃。合成乙烯基亚磺酰氧化物的过程较为复杂,去磷酸化生成二氟亚甲基同系物的尝试伴随着推动反应完成的努力。