开发和优化了两种不同的方案,以满足在确定仲醇的绝对构型时对(1)高灵敏度或(2)方便利用的需求。第一种协议使用竞争对映选择性转化(CEC)方法来确定纳米分子规模的构型。使用50μL微型注射器作为反应容器,以145 nmol的底物进行反应,并通过薄层色谱法对快速反应进行定性确定绝对构型。该方案使以前的CEC方法研究所需的材料减少了50倍。用苄基和β-芳基体系评估了该方法。第二种方案经过优化,可满足从业药物化学家的需求。开发了一种一次性使用的CEC套件,1 H NMR光谱法和薄层色谱法。为微注射器方案开发的CEC反应条件和一次性试剂盒均显示与底物中拟一级动力学一致的数据。因此,对于底物的灵敏度的下限仅受有效检测醇底物与酯产物之间的反应转化的能力的限制。
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.
Concise Synthesis of the Isothiourea Organocatalysts Homobenzotetramisole and Derivatives
作者:Beatrice Ranieri、Omar Robles、Daniel Romo
DOI:10.1021/jo400603n
日期:2013.6.21
A concise approach to the synthesis of homobenzotetramisole and derivatives is described. Our strategy features a one-pot acylation–cyclization of 2-aminobenzothiazole with α,β-unsaturatedacid chlorides to afford annulated pyrimidones. Subsequent Grignard addition followed by acid-promoted dehydration and reduction provides good overall yields of the title compounds in three steps and in quantities
Isothiourea-Catalyzed Enantioselective Carboxy Group Transfer
作者:Caroline Joannesse、Craig P. Johnston、Carmen Concellón、Carmen Simal、Douglas Philp、Andrew D. Smith
DOI:10.1002/anie.200904333
日期:2009.11.9
Transferable skills: Enantiomerically pure isothioureas promote the O‐ to C‐carboxyl grouptransfer of oxazolyl carbonates with excellent levels of enantiocontrol (see scheme). The origin of the enantioselectivity of this process was probed mechanistically and rationalized computationally.
Kinetic Analysis of the HBTM-Catalyzed Esterification of an Enantiopure Secondary Alcohol
作者:Alexander J. Wagner、Scott D. Rychnovsky
DOI:10.1021/ol402643n
日期:2013.11
A detailed kineticanalysis of the homobenzotetramisole-mediated esterification of the enantiopuresecondaryalcohol (1R,2S)-2-phenylcyclohexanol is presented. The results of this analysis show that the reaction is first order in the homobenzotetramisole catalyst, first order in (1R,2S)-2-phenylcyclohexanol, and first order in propionic anhydride. Initial rates, the turnover frequency of the catalyst