A General Catalytic Method for Highly Cost‐ and Atom‐Efficient Nucleophilic Substitutions
作者:Peter H. Huy、Isabel Filbrich
DOI:10.1002/chem.201800588
日期:2018.5.23
A general formamide‐catalyzed protocol for the efficient transformation of alcohols into alkyl chlorides, which is promoted by substoichiometric amounts (down to 34 mol %) of inexpensive trichlorotriazine (TCT), is introduced. This is the first example of a TCT‐mediated dihydroxychlorination of an OH‐containing substrate (e.g., alcohols and carboxylic acids) in which all three chlorine atoms of TCT
[EN] METHOD OF CONVERTING ALCOHOL TO HALIDE<br/>[FR] PROCÉDÉ DE CONVERSION D'UN ALCOOL EN HALOGÉNURE
申请人:UNIV SAARLAND
公开号:WO2016202894A1
公开(公告)日:2016-12-22
The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
Direct asymmetric α-chlorination of aryl aceticacidderivatives was achieved with a novel trinary activation system consisting of a catalytic amount of NiCl2/(R)-BINAP, Et3SiOTf, and a tertiary amine base. The reaction smoothly afforded the chlorinated compound in good yield with up to 89 % ee. Application of this reaction to a less acidic crotonic acidderivative gave the β,γ-unsaturated α-chlorinated
suppressing effect for α-chlorination and -bromination due to undesired halogenbonding. This strategy provides facile access to α-halogenated compounds in high yield with excellent enantioselectivity. X-ray crystallographic and ESR analyses of the catalyst complexes suggest that the release of two counteranions (2TfO–) from the copper(II) center might be crucial for the efficient activation of N-acyl-3
描述了新型手性 π-铜 (II)-π 配合物催化的N-酰基-3,5-二甲基吡唑的对映选择性 α-氯化和 -溴化。Cu(OTf) 2与 3-(2-萘基) -l-丙氨酸衍生的酰胺的 π-铜(II)-π 络合极大地增加了路易斯酸度并在没有外部碱的情况下触发了烯醇化物的原位生成,由于不希望的卤素键合,它对α-氯化和-溴化具有抑制作用。该策略提供了以高产率轻松获得α-卤代化合物的方法,并具有出色的对映选择性。催化剂配合物的 X 射线晶体学和 ESR 分析表明,释放了两种抗衡阴离子(2TfO-) 来自铜 (II) 中心可能对N-酰基-3,5-二甲基吡唑的有效活化至关重要。
1,2-Dimethoxy-4,5-dimethylene: a new protecting group for acyclic amino acid derivatives prepared by Stevens rearrangement
A newprotectinggroup, 1,2-dimethoxy-4,5-dimethylene, for acyclic amino acid derivatives could be introduced by N,N-dialkylation with 1,2-bis(bromomethyl)-4,5-dimethoxybenzene (1) and removed via amine de-alkylation with acyl chlorides. The method can be used with base-induced [2,3] and [1,2] Stevens rearrangement products.