Synthesis of 3-carbonyl pyrazole-5-phosphonates via 1,3-dipolar cycloaddition of Bestmann–Ohira reagent with ynones
作者:Mukund M.D. Pramanik、Ruchir Kant、Namrata Rastogi
DOI:10.1016/j.tet.2014.05.095
日期:2014.8
Bestmann–Ohira reagent. The reaction offers a convenient route for the synthesis of regioisomerically pure 3,5-disubstituted or 3,4,5-trisubstituted pyrazoles in excellent yields. However, di-ynones and molecules possessing both ynone and enone functionalities provide only monocycloaddition products, whereas another multiple bond undergoes Michael addition with the methoxide anion.
目前的工作探索了迄今尚未发现的与Bestmann–Ohira试剂成对的双极性亲和性炔酮的反应性。该反应提供了以优异的产率合成区域异构纯的3,5-二取代的或3,4,5-三取代的吡唑的简便途径。然而,二炔酮和同时具有炔酮和烯酮官能团的分子仅提供单环加成产物,而另一个多重键与甲醇根阴离子进行迈克尔加成。