Reactive dienophiles containing a difluoromethylenephosphonato group
作者:Kevin Blades、Thierry P. Lequeux、Jonathan M. Percy
DOI:10.1039/cc9960001457
日期:——
New dienophiles containing the difluoromethylenephosphonato group are synthesised from readily-available starting materials and cycloadditions with reactive dienes are executed successfully.
新的含有二氟亚甲基膦酸酯基团的二烯亲电体从易于获得的原料合成,并成功地与反应性二烯进行环加成反应。
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.
Facile syntheses of α,α-difluoro-β-ketophosphonates
作者:Thierry P. Lequeux、Jonathan M. Percy
DOI:10.1039/c39950002111
日期:——
The cerium-mediated reaction between lithio (diethyldifluoromethyl)-phosphonate 2 proceeds smoothly to afford good yields of ketophosphonates; the reaction with DMF led to the formation of the corresponding aldehyde which was isolated as a hydrate with interesting and useful properties.
1,3-Dipolar Cycloaddition of Diazomethane to 1,1-Difluoroallylphosphonates: Application to Synthesis of Cyclopropane Derivatives Having a Diethoxyphosphoryldifluoromethylene Unit
1,3-Dipolarcycloaddition of diazomethane to (1,1-difluoroallyl)phosphonates was examined to give pyrazolines functionalized by a diethoxyphosphoryldifluoromethylene unit. The pyrazolines were transformed to the cyclopropane derivatives possessing a diethoxyphosphoryldifluoromethylene functionality by photolysis.