B/N Lewis pairs have been discovered to catalyze rapid epimerization of meso-lactide (LA) or LA diastereomers quantitatively into rac-LA. The obtained rac-LA can be kinetically polymerized into poly(L-lactide) and optically resolved D-LA, with a high stereoselectivity factor kL/kD of 53 and an ee value of 91% at 50.6% monomer conversion, by a bifunctional chiral catalyst. The epimerization and enantioselective polymerization can be coupled into a one-pot process for transforming meso-LA directly into poly(L-lactide) and D-LA.
研究发现,B/N Lewis 对可催化中-内酰胺(
LA)或
LA 非对映异构体快速外嵌合,定量生成 rac-
LA。在双功能手性催化剂的作用下,得到的 rac-
LA 可被动力学聚合成聚(L-内酰胺)和光学分辨的 D-
LA,立体选择性系数 kL/kD 高达 53,在单体转化率为 50.6% 时,ee 值为 91%。表聚和对映体选择性聚合可以耦合为一个一锅工艺,直接将介壳烯烃转化为聚(L-内酰胺)和 D-
LA。