The asymmetric allenylboration of representative aldehydes with the stable, storable 1 is reported. Easily and efficiently prepared in either enantiomeric form from the air-stable crystalline 4 through simple Grignard procedures, 1 gives 6 cleanly. The latter is easily isolated in high yield and ee with predictable stereochemistry. The procedure also regenerates 4 for its direct conversion back to
报道了具有稳定的,可储存的1的代表性醛的不对称烯丙基
硼化。通过简单的
格氏试剂,由空气稳定的晶体4轻松有效地以对映体形式制备1,得到6干净。后者易于以高产率分离,并且具有可预测的立体
化学反应。该程序还再生了4,使其直接转化回1,并促进了伪
麻黄碱的有效回收。净过程是
烯丙基溴化镁不对称加成到醛中的合成等价物。[反应:看文字]