Insight into the Mechanism of the Asymmetric Ring-Opening Aminolysis of 4,4-Dimethyl-3,5,8-trioxabicyclo[5.1.0]octane Catalyzed by Titanium/BINOLate/Water System: Evidence for the Ti(BINOLate)<sub>2</sub>-Bearing Active Catalyst Entities and the Role of Water
作者:Hongli Bao、Jing Zhou、Zheng Wang、Yinlong Guo、Tianpa You、Kuiling Ding
DOI:10.1021/ja801847r
日期:2008.8.1
(R)-3,3',6,6'-D4-BINOL. Finally, the reactivity differences between several couples of epoxide/amine combinations were tentatively rationalized on the basis of the arguments on their relative coordination preferences, and several other aliphatic amines were also found to efficiently ring-open the titled epoxide in excellent enantioselectivities. The results from this study are expected to shed some light
4,4-二甲基-3,5,8-三氧杂双环[5.1.0]辛烷与苄胺的对映选择性开环氨解机制,由对映纯的BINOL混合物原位生成的钛-BINOLate物种催化(1 ,1'-bi-2-naphthol)、Ti(OiPr)4 和 H2O 在甲苯中存在苄胺的情况下,使用反应曲线测量、非线性效应 (NLE) 研究和溶液 (1) 的组合进行详细研究H NMR 分析、电喷雾电离质谱 (ESI-MS) 以及从配合物 L(a)/Ti/L(b) 的动态催化剂库筛选获得的结果(L(a) 或 L(b) =手性二醇配体)。发现 BINOL 与钛的比例以及催化体系中水的存在与否对反应的反应性和对映选择性都有深远的影响。NLE 研究表明,参与催化的钛物种应该包含一个以上的 BINOL 单元,无论是在催化循环内还是在催化循环的外围。催化系统的 ESI-MS 分析提供了强有力的支持,支持带有 Ti(BINOLate)2 部分的