Division of Chemical Process Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan.
J Org Chem. 2011 Dec 16;76(24):10312-8. doi: 10.1021/jo201940w. Epub 2011 Nov 11.
Kinetic resolution of sterically hindered racemic α-tert-alkyl-α-hydroxy esters is performed by enantiomer-selective carbamoylation with the t-Bu-Box-Cu(II) catalyst (Box = bis(oxazoline)). The reaction with 0.5 equiv of n-C(3)H(7)NCO is carried out with a substrate-to-catalyst molar ratio of 500-5000 at -20 to 25 °C. The high enantiomer-discrimination ability of the catalyst achieves an excellent stereoselectivity factor (s = k(fast)/k(slow)) of 261 in the best case. A catalytic cycle for this reaction is proposed.
通过使用 t-Bu-Box-Cu(II)催化剂（Box = 双恶唑啉）对立体位阻的外消旋α-叔-烷基-α-羟基酯进行对映选择性氨甲酰化反应，可以实现动力学拆分。在 -20 至 25°C 下，以底物与催化剂的摩尔比为 500-5000，用 0.5 当量的 n-C(3)H(7)NCO 进行反应。催化剂的高对映体选择性实现了最佳情况下高达 261 的出色立体选择性因子（s = k(fast)/k(slow)）。提出了该反应的催化循环。
