Alkylative carboxylation of ynamides with CO2 and dialkylzinc reagents using a N-heterocyclic carbene (NHC)-copper catalyst has been developed. A variety of ynamides, both cyclic and acyclic, undergo this transformation under mild conditions to afford the corresponding α,β-unsaturated carboxylic acids, which contain the α,β-dehydroamino acid skeleton. The present alkylative carboxylation formally consists of Cu-catalyzed carbozincation of ynamides with dialkylzinc reagents with the subsequent nucleophilic carboxylation of the resulting alkenylzinc species with CO2 . Dialkylzinc reagents bearing a β-hydrogen atom such as Et2 Zn and Bu2 Zn still afford the alkylated products despite the potential for β-hydride elimination. This protocol would be a desirable method for the synthesis of highly substituted α,β- dehydroamino acid derivatives due to its high regio- and stereoselectivity, simple one-pot procedure, and its use of CO2 as a starting material.
The first example of cobalt-catalyzed
selective hydrogenation of
nitriles to secondary imines is reported. The results demonstrate
the significantly different selectivity compared with the previously
reported cobalt catalytic system during the nitrile hydrogenation.
A variety of aromatic and aliphatic nitriles are hydrogenated to the
corresponding secondary imines.
The alkylative carboxylation of ynamidesa nd allenamides with CO 2 anda lkylzinc halidesc atalyzedb ya copperc atalystw as developed.Avariety of alkylzinc halides bearingf unctional groups were used for this transformation to afford a,b-unsaturated carboxylic acids, which contain the a,b-dehydroamino acid skeleton, introducing the corresponding alkyl group and CO 2 across the carbon-carbon triple or double bond.T his alkylative carboxylation formally consists of Cu-catalyzed carbozincation of ynamides or allenamides with alkylzinch alidesa nd the subsequentn ucleophilic carboxylation of the resulting alkenylzinc speciesw ith CO 2 .T his protocol would be au seful methodf or the synthesis of a,b-dehydroamino acid derivatives possessing af unctionalized alkyl groupd ue to the high regio-and stereoselectivity,s imple one-pot procedure as well as the use of CO 2 as as tarting material.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.
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