Chiral ligands derived from abrine. Part 7: Effect of O, S, N in aromatic ring substituents at C-1 on enantioselectivity induced by tetrahydro-β-carboline ligands in diethylzinc addition to aldehydes
作者:H.J. Zhu、B.T. Zhao、G.Y. Zuo、C.U. Pittman、W.M. Dai、X.J. Hao
DOI:10.1016/s0957-4166(01)00460-8
日期:2001.10
The effect of O, S and N atoms in aromatic ring substituents at C-1 position of tetrahydro-β-carboline ligands on the enantioselectivity of diethylzinc additions to benzaldehyde was studied when esters or tertiary alcohol functions were present at C-3. A mechanism is proposed to explain why the ester ligands 2c and 2d, in which the pyridyl N atom is at C′-2 in 2c and at C′-3 in 2d, catalyzed the addition
当在C-3处存在酯或叔醇官能团时,研究了四氢-β-咔啉配体的C-1位芳香环取代基中的O,S和N原子对二乙基锌加成苯甲醛的对映选择性的影响。提出了一种机制来解释为什么吡啶基N原子位于2c的C'-2和位于2d的C'-3的酯配体2c和2d催化二乙基锌与苯甲醛的加成反应而形成(R) -和(S1-苯基-1-丙醇的β-对映体。还提出了一种解释,即在添加二乙基锌期间,叔醇3c诱导的中等对映选择性与3d诱导的非常小的对映选择性(在C-1处具有3-吡啶基功能)有关。C-1处的-CH 2 - t -Bu取代基导致很高的对映选择性。