1,8-Diazabicyclo[5.4.0]undecene Mediated Transesterification of<i>p</i>-Nitrophenyl Phosphonates: A Novel Route to Phosphono Esters
作者:Dan S. Tawfik、Zelig Eshhar、Alfonso Bentolila、Bernard S. Green
DOI:10.1055/s-1993-25982
日期:——
DBU (1,8-diazabicyclo[5.4.0]undecene) was found to efficiently mediate the transesterification of p-nitrophenyl (PNP) phosphonates by various alcohols. The reactions of bis-PNP phosphonates in the presence of DBU, using both primary and secondary alcohols, phenols and amines, proceed rapidly and with high yield to afford the corresponding monoalkyl/aryl mono-PNP phosphonates as sole products (1, Scheme 2). The resulting monoalkyl/aryl mono-PNP phosphonates can be further reacted with a second alcohol to give the corresponding differently disubstituted phosphonates 3, or selectively hydrolysed to yield the monoalkyl/aryl phosphonic acids 2. We have applied this chemistry to the preparation of a series of phosphono ester transition state analogues 11a-e (Scheme 3) that were used as haptens for raising catalytic antibodies.
研究发现 DBU(1,8-二氮杂双环[5.4.0]十一烯)能有效地介导对硝基苯(PNP)膦酸盐与各种醇的酯交换反应。在 DBU 的存在下,使用伯醇、仲醇、酚和胺对双-PNP 膦酸盐进行反应,反应速度快,产率高,可得到相应的单烷基/芳基单-PNP 膦酸盐作为唯一产物(1,方案 2)。生成的单烷基/芳基单-PNP 膦酸盐可进一步与第二种醇反应,得到相应的不同二取代膦酸盐 3,或选择性水解,得到单烷基/芳基膦酸 2。我们将这种化学方法应用于制备一系列膦酸酯过渡态类似物 11a-e(方案 3),这些类似物可用作催化抗体的触价物。