A New Synthetic Route to Enantiomerically Pure Axially Chiral 2,2‘-Bipyridine <i>N,N</i><i>‘</i>-Dioxides. Highly Efficient Catalysts for Asymmetric Allylation of Aldehydes with Allyl(trichloro)silanes
作者:Toyoshi Shimada、Asato Kina、Tamio Hayashi
DOI:10.1021/jo0300800
日期:2003.8.1
New axially chiral 2,2'-bipyridine N,N'-dioxides 1 were obtained in an enantiomerically pure form by way of cyclic diesters 6 or 7 which were formed by the esterification of diols 2 with (R)-2,2'-bis(chlorocarbonyl)-1,1'-binaphthalene (5). Epimerization of the kinetic products at the ester formation (R(nap),S(pyr))-6 to the thermodynamically stable isomers (R(nap),R(pyr))-7 was observed in refluxing
通过环二酯6或7以对映体纯的形式获得新的轴向手性2,2'-联吡啶N,N'-二氧化物1,其通过二醇2与(R)-2,2'-的酯化反应形成双(氯羰基)-1,1'-联萘(5)。在回流的甲苯中或存在下,在酯形成(R(nap),S(pyr))-6处的动力学产物差向异构体形成热力学稳定的异构体(R(nap),R(pyr))-7。三氟乙酸。发现在6和6′位置被苯基取代的N,N′-二氧化物1a之一具有高催化活性,并且对于醛与烯丙基(三氯)硅烷的不对称烯丙基化反应给出了烯丙基醇。