<i>N</i>-Heterocyclic Carbene-Catalyzed Generation of Homoenolates: γ-Butyrolactones by Direct Annulations of Enals and Aldehydes
作者:Stephanie S. Sohn、Evelyn L. Rosen、Jeffrey W. Bode
DOI:10.1021/ja044714b
日期:2004.11.1
generation of reactive homoenolates from alpha,beta-unsaturated aldehydes. The catalyst-bound homoenolate reacts with electrophilic aldehydes leading, via the key intermediacy of an activated carboxylate, to gamma-butyrolactones in good yields and stereoselectivities. Importantly, this process demonstrates an unprecedented reaction mode for the generation of nucleophilic carbanions with a multifunctional
Palladium-Catalyzed Conjugate Addition of Terminal Alkynes to Enones
作者:Lara Villarino、Rebeca García-Fandiño、Fernando López、José L. Mascareñas
DOI:10.1021/ol300988n
日期:2012.6.15
A practical protocol for the hydroalkynylation of enones using Pd catalysis is reported. The reaction proceeds efficiently with a variety of alkynes as well as with several cyclic and acyclic enones, providing synthetically relevant β-alkynyl ketones in good to excellent yields.
Oxidative alkynylation of acrylate esters with propargylic alcohols giving conjugated enyne esters was realized by use of a diene–rhodium catalyst. Propargylic alcohols were found to be useful alkynylating reagents in the present reaction to produce alkynylrhodium species via carbon–carbon bond cleavage. An excess of the acrylate ester worked as a hydride acceptor to reproduce the active rhodium species
We present an allylic polyfluoroarylation reaction with broad substrate scope and excellent functional group tolerance, using organozinc reagents under mild conditions. A catalytic amount of triphenylphosphine oxide efficiently promotes iodine-zinc exchange reaction between polyfluoroaryl iodide and dimethylzinc, and the resulting phosphine oxide-activated polyfluoroarylzinc undergoes substitution reaction with allylic halides to afford the corresponding polyfluoroarylated products. (C) 2015 Elsevier Ltd. All rights reserved.