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.