Preparation of Chiral α-Oxy-[<sup>2</sup>H<sub>1</sub>]methyllithiums of 99% ee and Determination of Their Configurational Stability
作者:Dagmar Kapeller、Roland Barth、Kurt Mereiter、Friedrich Hammerschmidt
DOI:10.1021/ja066183s
日期:2007.1.1
microscopically configurationally stable phosphinyloxy-substituted [2H1]methyllithiums, which rearranged to hydroxy-[1-2H1]methylphosphonates of ee > 98% (phosphate-phosphonate rearrangement). The N,N-diisopropylcarbamates of the enantiomeric tributylstannyl-[1-2H1]methanols were transmetalated to give carbamoyloxy-substituted chiral [2H1]methyllithiums, which were macroscopically configurationally stable for
(三丁基锡烷基)甲基 2,2,6,6-四甲基哌啶-1-羧酸盐在 -78 摄氏度下用 t-BuLi/TMEDA 金属化,并用衍生自 (R,R)-1,2-二环己基乙烷的混合硼酸盐进行硼酸化1,2-二醇和叔丁醇得到等量的非对映体硼酸酯 31/32。硼酸盐 31 和 32 用 LiBEt3D 还原,然后用碱性 H2O2 氧化,分别得到 99% ee 的 (S)- 和 (R)-三丁基甲锡烷基-[1-2H1] 甲醇。在 -78 和 0 摄氏度下用 n-BuLi 处理它们各自的磷酸盐得到微观构型稳定的膦酰氧基取代的 [2H1] 甲基锂,其重排为 ee > 98% 的羟基-[1-2H1]甲基膦酸盐(磷酸盐-膦酸盐重排) . 然后,对映体三丁基甲锡烷基-[1-2H1] 甲醇的 N-二异丙基氨基甲酸酯被金属转移,得到氨基甲酰氧基取代的手性 [2H1] 甲基锂,在 - 78 摄氏度,由苯甲醛诱捕实验推断。这些甲基锂的化学稳定性在