Herein,
we developed an efficient and selective nickel-catalyzed
monoalkylation of various primary alcohols with aryl and heteroaryl
amines together with diols and amino alcohol derivatives. Notably,
the catalytic protocol consisting of an earth-abundant and non-precious
NiBr2/L1 system enables the transformations
in the presence of hydroxyl, alkene, nitrile, and nitro functionalities.
As a highlight, we have demonstrated the alkylation of diamine, intramolecular
cyclization to N-heterocycles, and functionalization of complex vitamin
E, an (±)-α-tocopherol derivative. Preliminary mechanistic
studies revealed the participation of a benzylic C–H bond in
the rate-determining step.
The α-alkylation of ketones using an earth-abundant and nonprecious NiBr/L1 system is reported. This nickel-catalyzed reaction could be performed in gram scale and successfully applied in the synthesis of donepezil (Alzheimer's drug) and functionalization of steroid hormones and fatty acid derivatives. Synthesis of N-heterocycles, methylation of ketones, and one-pot double alkylation to bis-hetero aryl ketones using two different alcohols with a single catalyst broadens the scope of the catalytic protocol. Preliminary mechanistic studies using defined Ni-H species and deuterium-labeling experiments established the participation of the borrowing-hydrogen strategy.
Nickel-catalysed conversion of β- and γ-amino alcohols with ketones enables selective construction of pyrroles, pyridines and quinolines by liberation of hydrogen gas and water as sole by-products.
Herein we have developed
a Ni-catalyzed protocol for the synthesis
of linear ketones. Aryl, alkyl, and heteroaryl ketones as well as
alcohols yielded the monoselective ketones in up to 90% yield. The
catalytic protocol was successfully applied in to a gram-scale synthesis.
For a practical utility, applications of a steroid derivative, oleyl
alcohol, and naproxen alcohol were employed. Preliminary catalytic
investigations involving the isolation of a Ni intermediate and defined
Ni–H species as well as a series of deuterium-labeling experiments
were performed.
By employing ligands in the PdII‐mediated arylative isomerization of allyl alcohols, a milder and regioselective access to the versatile building blocks β‐aryl aldehydes and ketones was developed. This new and chelation‐controlled protocol enabled the compatibility of wide range of functionalities to generate dihydrochalcones, α‐benzyl‐α′‐alkyl acetones, dihydrocinnamaldehydes, and α‐benzyl β‐keto esters (from Baylis–Hillman adducts). A practical multigram synthesis of an intermediate for Propafenone was also demonstrated.
An efficient Fe-catalyzed
system is reported for direct α-olefination
of methyl-substituted N-heteroarenes with primary
alcohols. The catalytic dehydrogenative coupling enables a series
of functionalized E-olefinated N-heteroaromatics with excellent selectivity (>99%). Initial mechanistic
studies including deuterium-labeling experiments provide evidence
for the participation of the benzylic C–H/D bond of alcohols.
Ni-catalysed α-olefination of alkylheteroarenes with primary alcohols via dehydrogenative coupling is presented. A simple catalytic protocol gave good to excellent yields of E-selective olefins with olefin/alkane selectivity of >20 : 1.
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