709042-60-4Relevant academic research and scientific papers
Mechanistic Study of Nickel-Catalyzed Reductive Coupling of Ynoates and Aldehydes
Rodrigo, Sanjeewa K.,Guan, Hairong
, p. 5230 - 5235 (2017)
In this work, (1,5-hexadiene)Ni(SIPr) (SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene) is used in place of Ni(COD)2/SIPr·HBF4/KOtBu (COD = 1,5-cyclooctadiene) as a more robust catalyst for regioselective reductive coupling of ynoates and aldehydes with triethylsilane. The catalytic reaction of ethyl 3-(trimethylsilyl)propiolate and methyl 4-formylbenzoate shows first-order dependence on aldehyde and catalyst concentrations, inverse first-order dependence on [ynoate], and no dependence on [silane]. The kinetics data, coupled with deuterium-labeling experiments, support a mechanism involving dissociation of the ynoate from a catalytically dormant nickelacyclopentadiene intermediate prior to turnover-limiting formation of a catalytically active nickeladihydrofuran.
Quick installation of a 1,4-difunctionality via regioselective nickel-catalyzed reductive coupling of ynoates and aldehydes
Rodrigo, Sanjeewa K.,Guan, Hairong
, p. 8303 - 8309,7 (2020/10/15)
The development of efficient methods for the synthesis of molecules with 1,4-difunctionalities has been a dire need of the synthetic community. In this work, intermolecular reductive coupling of ynoates and aldehydes (in the presence of a silane) has been accomplished for the first time using catalytic amounts of Ni (COD)2, an N-heterocyclic carbene ligand, and PPh 3. High regioselectivity has been demonstrated for the multicomponent coupling reactions, and more than a dozen invaluable silyl-protected γ-hydroxy-α,β-enoates have been synthesized. This methodology provides a quick entry to many other 1,4-difunctional compounds and oxygen-containing five-membered rings. The intermediacy of metallacycles in the catalytic process has been established by deuterium-labeling experiments.
