Structure-enantioselectivity effects in 3,4-dihydropyrimido[2,1-b]benzothiazole-based isothioureas as enantioselective acylation catalysts
作者:Dorine Belmessieri、Caroline Joannesse、Philip A. Woods、Callum MacGregor、Caroline Jones、Craig D. Campbell、Craig P. Johnston、Nicolas Duguet、Carmen Concellón、Ryan A. Bragg、Andrew D. Smith
DOI:10.1039/c0ob00515k
日期:——
The catalytic activity and enantioselectivity in the kinetic resolution of (±)-1-naphthylethanol with a range of structurally related 3,4-dihydropyrimido[2,1-b]benzothiazole-based catalysts is examined. Of the isothiourea catalysts screened, (2S,3R)-2-phenyl-3-isopropyl substitution proved optimal, giving good levels of selectivity in the kinetic resolution of a number of secondary alcohols (S values up to >100 at ∼50% conversion). Low catalyst loadings (0.10–0.25 mol%) of the optimal isothiourea can be used to generate enantiopure alcohols (>99% ee) in good yields.
本文研究了一系列结构相关的3,4-二氢嘧咪啶[2,1-b]苯并噻唑基催化剂在对(±)-1-萘乙醇的动力学分辨过程中的催化活性和对映选择性。在筛选的异硫脲催化剂中,(2S,3R)-2-苯基-3-异丙基取代物表现出最佳效果,在多种二次醇的动力学分辨中实现了良好的选择性(S值在约50%转化率时可达到≥100)。最佳异硫脲催化剂的低负载量(0.10–0.25 mol%)可用于生成对映纯醇(对映体过量≥99%)且产率良好。