chiral non racemic N-Cbz-trifluoropyruvaldehyde-N,S-ketal1a (enantiomeric excess up to 74%) is a new trifluoro 3-C building block, which has been reacted with several Grignard reagents, stereoselectively affording the corresponding secondary carbinols 2. The N,S-ketal stereocentre, whose absolute stereochemistry has been determined by X-ray analysis of the α-phenylpropionate 3, is able to provide excellent
手性非外消旋的N -Cbz-
三氟丙酮醛-N,S-
缩酮1a(对映体过量高达74%)是一种新的三
氟3-C结构单元,已与几种
格氏试剂反应,立体选择性地提供了相应的二级
甲醇2。的Ñ,s ^ -ketal立构,其绝对立体
化学已经被α苯丙的X射线分析确定的3,能够提供优异的立体控制。高度立体选择性的对
甲苯硫基取代得到N -Cbz-苯基衍
生物2d,转化为三
氟去氧
麻黄碱(S,S)-5和-
麻黄碱(S,S)-6 。