Many carbenoid cyclopropanation reactions promoted by chiral catalysts give product mixtures reflecting impressive diastereo- and enantioselectivities. Few provide a single chiral product efficiently. This limitation has been overcome in cyclopropanations of styrene and isotopically labeled styrenes with α-diazoacetates. Convenient syntheses on a 20 g scale of each of four chiral isotopically labeled (1R)-menthyl (1S,2S)-2-phenylcyclopropanecarboxylates (the 1-d-3-13C, 1,(3S)-d2, 1,2,(3S)-d3, and 1,3,3-d3 isotopomers) of better than 99% ee have been realized.
许多由手性
催化剂促进的类卡宾环
丙烯化反应产生的产物混合物显示出令人印象深刻的非对称选择性和针对性的选择性。但很少有反应能高效地产生单一的手性产物。这一限制在与α-二
氮杂
乙酸酯的
苯乙烯和同位素标记
苯乙烯的环
丙烯化反应中得到了克服。已经成功合成了四种手性同位素标记的(1R)-薄荷基(1S,2S)-
2-苯基环丙烷羧酸酯(1-d-3-13C、1,(3S)-d2、1,2,(3S)-d3和1,3,3-d3同位素异构体),其对映体过量(ee)均超过99%。