Trimethylsilyl chloride promoted synthesis of α-branched amines by nucleophilic addition of organozinc halides to nitrones
作者:Ying Fu、Yanhua Liu、Yaojuan Chen、Helmut M. Hügel、Minzhu Wang、Danfeng Huang、Yulai Hu
DOI:10.1039/c2ob26202a
日期:——
general procedure for the nucleophilicaddition of organozinc halides with nitrones in the presence of trimethylsilyl chloride has been developed. Trimethylsilyl chloride was found to be both an indispensable reaction promoter and a ready hydroxylamine protective agent in these reactions. The produced O-(trimethylsilyl)hydroxylamines can be easily reduced into corresponding amines just by a zinc–copper
Cobalt−Xantphos-Catalyzed, LiCl-Mediated Preparation of Arylzinc Reagents from Aryl Iodides, Bromides, and Chlorides
作者:Meng-Yi Jin、Naohiko Yoshikai
DOI:10.1021/jo102417x
日期:2011.4.1
A cobalt−Xantphos-catalyzed, LiCl-mediated system has been developed for the direct and expedient preparation of arylzinc reagents in THF from the corresponding aryl iodides, bromides, and chlorides. Owing to the use of THF as a versatile solvent, the thus-formed arylzinc reagents displayed a high degree of compatibility with a variety of conventional as well as newly emerging metal-catalyzed cross-coupling
Symmetrical diaryl ketones were prepared by a cross-coupling reaction between aryl bromides and ethyl chloroformate. This new method, which uses a catalyst composed of CoBr2 and a bipyridine ligand along with readily available starting materials, allows for the synthesis of a variety of symmetrical diaryl ketones in moderate to excellent yields (37–99 %) under mild conditions. This reaction, in which
Herein, a cobalt‐catalysed Negishi‐type cross‐coupling of amide derivatives is described. Apart from being the first example of cobalt‐catalysed Negishi‐type coupling of amides, the process described employs a unique, simple, and cheap catalytic system to perform both the organozinc formation and the Negishi‐type coupling. Indeed, the same cobalt(II) bromide salt used to form the arylzinc species from
<i>Cine</i> Substitution with Arylzinc Reagents: Scope and Mechanistic Studies
作者:Santiago Barroso、Sébastien Lemaire、Vittorio Farina、Andreas K. Steib、Romain Blanc、Paul Knochel
DOI:10.1021/acs.joc.6b00074
日期:2016.4.1
of arylzinc reagents bearing electron-donating substituents to react in a Friedel–Crafts fashion (cine) with electrophiles like perpivaloylated glucoside bromide and benzhydryl bromides in competition with organometalliccoupling (ipso) is shown. The stereoelectronic factors required to promote the cine reactivity versus the classical ipso, and the mechanism of this alternative pathway, have been investigated