Uncatalyzed conjugate addition of organozinc halides to enones in DME: a combined experimental/computational study on the role of the solvent and the reaction mechanism
calculations, prompted by the experimental aggregation study, revealed an unexpected reactionmechanism, where the coordinating capabilities of DME stabilize a transition state involving two organozinc moieties, lowering the activation energy of the reaction with respect to that seen for THF, enough to explain the fast and quantitative reactions observed experimentally and the different behaviors of
Primary-Secondary Diamine Catalyzed Enantioselective Synthesis of Substituted Cyclohex-2-enones by Cascade Michael–Aldol–Dehydration of Ketones with Chalcones
作者:Sandip Wagh、Ganesh Dhage
DOI:10.1055/s-0036-1588976
日期:2017.7
A simple primary-secondary diamine organocatalyst catalyzes the cascade Michael–aldol–dehydration of chalcones and unmodified ketones to produce substituted cyclohex-2-enones under mild conditions with good yields and high enantio- and/or diastereoselectivities. The success of the catalyst system is possibly due to simultaneous activation of the electrophilic chalcone by iminium formation and the nucleophilic
Reaction condition controlled nickel(<scp>ii</scp>)-catalyzed C–C cross-coupling of alcohols
作者:Meng-Juan Zhang、Hong-Xi Li、David J. Young、Hai-Yan Li、Jian-Ping Lang
DOI:10.1039/c9ob00418a
日期:——
methodology employing a Ni(II) 4,6-dimethylpyrimidine-2-thiolate cluster catalyst under different reaction conditions. This catalyst could tolerate a wide range of substrates and exhibited a high activity for the annulation reaction of secondary alcohols with 2-aminobenzyl alcohols to yield quinolines. This work is an example of precise chemoselectivity control by careful choice of reaction conditions.
Highly enantioselective synthesis of γ-substituted butenolides via the vinylogous Mukaiyama–Michael reaction catalyzed by a chiral scandium(iii)–N,N′-dioxide complex
A highly efficient catalytic asymmetric vinylogous Mukaiyama–Michael reaction of the 2-silyloxyfuran with chalcone derivatives, catalyzed by a chiralN,N′-dioxide–scandium(III) complex, has been accomplished which tolerates a wide range of substrates. The reaction proceeds with complete regioselectivities, excellent diastereoselectivities (up to >99 : 1 dr) and good to excellent enantioselectivities
Addition reactions of organic carbanion equivalents via hydrazones in water
作者:Yi-Zhan Wang、Qi Liu、Liang Cheng、Song-Chen Yu、Li Liu、Chao-Jun Li
DOI:10.1016/j.tet.2020.131889
日期:2021.1
The addition of organometallic reagents to unsaturated bonds is one of the most powerful tools for carbon–carbon bondformations. Alkylation throughorganometallic reagents requires stoichiometric quantity of metal and tedious anhydrous operation in most cases. Here, we report “umpolung” nucleophilic additions of hydrazones to Michael acceptors, carbonyls and imines in water. Under the catalysis of