Study on the synthesis of nonracemic C2-symmetric 1,1′-binaphthyl-2,2′-diyl bridged ferrocene. Stereochemical result of the cross-coupling reactions controlled by Pd(II) or Pd(IV) complex intermediacy
作者:P Kasák、R Mikláš、M Putala
DOI:10.1016/s0022-328x(01)00926-3
日期:2001.12
Palladium catalyzed Negishi, Suzuki and Stille cross-coupling reactions of enantiopure 2,2′-diiodo-1,1′-binaphthyl with the corresponding 1,1′-dimetalloferrocenes gave the C2-symmetric binaphthyl bridged ferrocene 1-1,1′-(1,1′-binaphthyl-2,2′-diyl)ferrocene (1). The latter was obtained by Stille coupling with the bis(trimethylstannyl) derivative but not with the bis(tributylstannyl) one. Products of
钯催化对映纯2,2'-二碘-1,1'-联萘与相应的1,1'-双金属二茂铁的Negishi,Suzuki和Stille交叉偶联反应,得到C 2对称的双萘桥联二茂铁1-1,1' -(1,1'-联萘-2,2'-二基)二茂铁(1)。后者是通过Stille与双(三甲基锡烷基)衍生物偶联而未与双(三丁基锡烷基)衍生物偶联而获得的。在这两种情况下,都获得了从锡到双萘基的烷基转移产物。这些在1,1′-联萘的2和2′位上的交叉偶联反应的立体化学结果取决于1,1′-双金属二茂铁的反应性。Negishi偶联以立体保守的方式进行(提供对映纯产品1)。在与反应性较低的硼和锡有机金属化合物反应期间,发生了联萘基部分的完全消旋。提议的不同反应途径包括前者中的C 1对称钯(II)中间体和后者情况中的构型不稳定的C 2对称钯(IV)环状中间体。与交叉偶联反应相反,二茂铁与对映纯1,1'-联萘-2,2'-双重氮盐的自由基芳基