Mechanism-Based Enantiodivergence in Manganese Reduction Catalysis: A Chiral Pincer Complex for the Highly Enantioselective Hydroboration of Ketones
作者:Vladislav Vasilenko、Clemens K. Blasius、Hubert Wadepohl、Lutz H. Gade
DOI:10.1002/anie.201704184
日期:2017.7.10
A manganese alkyl complex containing a chiralbis(oxazolinyl‐methylidene)isoindoline pincer ligand is a precatalyst for a catalytic system of unprecedented activity and selectivity in the enantioselective hydroboration of ketones, thus producing preparatively useful chiral alcohols in excellent yields with up to greater than 99 % ee. It is applicable for both aryl alkyl and dialkyl ketone reduction
含有手性双(恶唑啉基-亚甲基)异二氢吲哚钳位配体的锰烷基络合物是酮对映选择性氢硼化反应中空前的活性和选择性的催化体系的预催化剂,从而以高达99的高收率生产了制备有用的手性醇。 %ee。它适用于在温和的反应条件下(TOF> 450 h -1在-40°C下)。富含地球的贱金属催化剂在极低的催化剂负载量(低至0.1 mol%)下运行,并且具有很高的官能团耐受性。有证据表明存在两种不同的锰催化氢化物转移机理,并介绍了它们在选择性确定步骤中对映体控制的作用。
Alkylation des ions carboxylates par les sels de sulfonium: influence des sels de cuivre
Sulfonium salts are extremely powerful alkylating agents, particularly in the two-phase technique both solid-liquid and liquid-liquid). Alkylation of carboxylate salts by sulfonium salts does not show very large dependence on ratio of reactivities of various groups attached to the sulfur and mixtures of esters are often obtained. In the presence of copper(I) salts, there is a strong acceleration of
Highly Enantioselective Rh-Catalysed Hydrogenation of 1-Alkyl Vinyl Esters Using Phosphine-Phosphoramidite Ligands
作者:Tina Maria Konrad、Pascal Schmitz、Walter Leitner、Giancarlo Franciò
DOI:10.1002/chem.201303066
日期:2013.9.27
MatPhos, a good mate for hard tasks: The asymmetric hydrogenation of 1‐alkyl vinyl esters, thwarted so far by mediocre ee values and low activities, can now be achieved with MatPhos/Rh catalysts with ee values of 96–99 % for a variety of substrates at low catalyst loadings (0.1–1 mol %) and under mild conditions (5–20 bar H2, room temperature). After hydrolysis, the corresponding chiral secondary alkyl
MatPhos,是完成艰苦任务的理想伴侣:迄今为止,由于中等ee值和低活性,阻碍了1-烷基乙烯基酯的不对称氢化,现在可以使用ee值为96–99%的MatPhos / Rh催化剂来实现在低催化剂负载量(0.1-1 mol%)和温和条件(5-20 bar H 2,室温)下制备底物。水解后,可以高对映体纯度获得相应的手性仲烷基醇,为获得这一重要产品类别提供了一条通用而实用的途径。
Nucleophilic Substitution Reactions of (Alkoxymethylene)dimethylammonium Chloride
作者:Anthony G. M. Barrett、D. Christopher Braddock、Rachel A. James、Nobuyuki Koike、Panayiotis A. Procopiou
DOI:10.1021/jo980583j
日期:1998.9.1
The use of imidate esters as potential replacements for diethyl azodicarboxylate and triphenylphosphine in the Mitsunobu reaction is described. A series of secondary alcohols were allowed to react with (chloromethylene)dimethylammonium chloride, generated from dimethylformamide (DMF) and oxalyl chloride, to give imidate esters. Reaction of these salts with potassium benzoate or potassium phthalimide
Nucleophilic substitution of (alkoxymethylene)dimethylammonium chloride with carboxylate salts: a convenient procedure for the synthesis of esters with inversion of configuration
作者:Anthony G. M. Barrett、Nobuyuki Koike、Panayiotis A. Procopiou
DOI:10.1039/c39950001403
日期:——
Secondary alcohols are converted into benzoate esters with inversion of configuration via sequential reaction with (chloromethylene)dimethylammonium chloride and potassium benzoate.