Copper(I)-Catalyzed Boryl Substitution of Unactivated Alkyl Halides
摘要:
Borylation of alkyl halides with diboron proceeded in the presence of a copper(I)/Xantphos catalyst and a stoichiometric amount of K(O-t-Bu) base. The boryl substitution proceeded with normal and secondary alkyl chlorides, bromides, and iodides, but alkyl sulfonates did not react. Menthyl halides afforded the corresponding borylation product with excellent diastereoselectivity, whereas (R)-2-bromo-5-phenylpentane gave a racemic product. Reaction with cyclopropylmethyl bromide resulted in ring-opening products, suggesting the reaction involves a radical pathway.
Sulfonyl halide synthesis by thiol oxyhalogenation using NBS/NCS – i PrOH
作者:Carolina Silva-Cuevas、Carlos Perez-Arrieta、Luis A. Polindara-García、J. Armando Lujan-Montelongo
DOI:10.1016/j.tetlet.2017.04.087
日期:2017.6
A rapid and facile method provides a general route to sulfonyl bromides/chlorides by the oxidation of thiols using NXS – ROH (X = Br,Cl, R = iPr) as an oxyhalogenation reagent. Control experiments suggest that the alcohol component is the source of oxygen. The proposed method enable the access to structurally diverse sulfonyl bromides and chlorides including challenging examples, inaccessible by other
一种快速而简便的方法,是使用NXS – ROH(X = Br,Cl,R = i Pr)作为氧卤代试剂氧化硫醇,从而提供了磺酰溴/氯化物的一般途径 。对照实验表明,酒精成分是氧气的来源。所提出的方法使得能够获得结构上不同的磺酰溴和氯化物,包括具有挑战性的实例,这是其他合成方法所无法达到的。
Iron(III)-Catalyzed Halogenations by Substitution of Sulfonate Esters
作者:Nuria Ortega、Andrés Feher-Voelger、Margarita Brovetto、Juan I. Padrón、Victor S. Martín、Tomás Martín
DOI:10.1002/adsc.201000740
日期:2011.4.18
A novel halogenation reaction from sulfonates catalyzed by iron(III) is described. The reaction can be performed as a stoichiometric or a catalytic version. This reaction provides a convenient strategy for the efficient access to structurally diverse secondary chlorides, bromides and iodides. The stereochemical course of the reaction is governed by the substrate and the experimental conditions. Secondary
Phosphide anions, prepared by an action of sodium dihydridobis(2-methoxyethanolato)aluminate on derivatives of phosphine, phosphine oxide, or phosphorus esters, react with primary and secondary alkyl halides to produce phosphine derivatives having a newly formed phosphorus-carbon bond. The reactivity increases in the order of chloride
Photoinduced Radical Borylation of Alkyl Bromides Catalyzed by 4‐Phenylpyridine
作者:Li Zhang、Zhong‐Qian Wu、Lei Jiao
DOI:10.1002/anie.201912564
日期:2020.1.27
Utilizing pyridine catalysis, we developed a visible-light-induced transition-metal-free radical borylation reaction of unactivated alkyl bromides that features a broad substrate scope and mild reaction conditions. Mechanistic studies revealed a novel nucleophilic substitution/photoinduced radical formation pathway, which could be utilized to trigger a variety of radical processes.