A number of optically pure 1,3-diols have been synthesized and used as catalysts in the asymmetric addition of diethylzinc to aromatic aldehydes. Enantiomeric excesses of up to 92% of (R)-1-phenylpropan-1-ol were obtained with anisylbicyclo[2.2.2]octanediol (14) as a catalyst. Using 2-picolylbicyclo[2.2.2]ocatanediol (16) as the catalyst resulted in a reversal of the stereoselectivity, yielding (S)-1-phenylpropan-1-ol in 83% ee. A pronounced positive non-linear effect was observed when varying the enantiomeric purity of catalyst 14.
合成了一些光学纯的1,3
-二醇,并将其用作对映选择性添加
二乙基锌于芳香醛的催化剂。以苯基双环[2.2.2]八醇(14)作为催化剂时,获得了高达92%的(R)-1-苯基
丙醇的对映体过量。使用2-
吡啶基双环[2.2.2]八醇(16)作为催化剂则使立体选择性发生了逆转,得到了83%对映体过量的(S)-1-苯基
丙醇。当改变催化剂14的对映体纯度时,观察到了明显的正非线性效应。