Isoselenazolones as Catalysts for the Activation of Bromine: Bromolactonization of Alkenoic Acids and Oxidation of Alcohols
作者:Shah Jaimin Balkrishna、Ch Durga Prasad、Piyush Panini、Michael R. Detty、Deepak Chopra、Sangit Kumar
DOI:10.1021/jo301486c
日期:2012.11.2
selenium powder. The catalytic activity of the various isoselenazolones was studied in the bromolactonization of pent-4-enoic acid. Isoselenazolone 9 was studied as a catalyst in several reactions: the bromolactonization of a series of alkenoicacids with bromine or N-bromosuccinimide (NBS) in the presence of potassium carbonate as base, the bromoesterification of a series of alkenes using NBS and a variety
A catalytic system consisting of bis(4-methoxyphenyl)selenide and 4-(dimethylamino)pyridine (DMAP) has been developed for the regioselective synthesis of medium-sized bromo/iodo lactones and bromooxepanes possessing high transannular strain. 77Se NMR, mass spectrometry...
the first time, telluronium cations demonstrated impressive catalytic properties at low loadings in three benchmark reactions: the Friedel–Crafts bromination of anisole, the bromolactonization of ω-unsaturated carboxylic acids and the aza-Diels–Alder between Danishefsky'sdiene and imines. The ability of telluronium cations to interact with a Lewis base through chalcogen bonding was demonstrated on the
硫属元素键合是由缺乏电极的硫属元素原子和路易斯碱之间发生的非共价相互作用引起的。在硫属元素中,碲是最强的路易斯酸,但 Te 基化合物很少用作有机催化剂。碲阳离子首次在三个基准反应中在低负载量下表现出令人印象深刻的催化性能:苯甲醚的 Friedel-Crafts 溴化、ω-不饱和羧酸的溴内酯化以及丹麦谢夫斯基二烯和亚胺之间的 aza-Diels-Alder。基于多核(17 O、31 P 和125 Te)NMR 分析和 DFT 计算证明了碲阳离子通过硫属元素键合与路易斯碱相互作用的能力。
Nitroxyl Catalysts for Six-Membered Ring Bromolactonization and Intermolecular Bromoesterification of Alkenes with Carboxylic Acids
includes a six-memberedring bromolactonization of alkenyl carboxylic acids catalyzed by AZADO as the nitroxyl radical catalyst, and an intermolecular bromoesterification of alkenes with carboxylic acids using NMO as the N-oxide catalyst. We also accomplished a remote diastereoselective bromohydroxylation via an AZADO-catalyzed six-memberedring bromolactonization and a subsequent ring cleavage reaction
developed via the oxidative umpolung of bromide using alkali metal bromide and inorganic oxidant to provide the corresponding cyclization products in high yields. In particular, the use of AcOEt, the solvent of choice for green sustainable reactions, led to the high reactivities of the present reactions. This methodology is highly recommended for green sustainable chemistry because it uses stable and non-hazardous