A rhodium-catalyzed highly regio- and stereoselective intermolecular hydrosilylation of internal ynamides has been developed. With the neutral rhodium complex [Rh(CO)2Cl]2 as a catalyst and the bulky silanes as reactants, various ynamides underwent hydrosilylation smoothly at room temperature with an excellent β-regioselectivity and anti-stereoselectivity. The synthetically versatile β-silyl (Z)-enamide
The copper(I)-catalyzed hydroboration of alkynamides with B2pin2 afforded the alkenamide boronates in 66% to nearly quantitative yields with high regio- and stereo-selectivity. It was interesting to note that the regio-selectivity of the reaction is opposite to that observed in the carbometallation reaction of alkynamides, and the resulting alkenyl boronates provided access to alpha,beta-disubstituted
Ynamide Preactivation Allows a Regio- and Stereoselective Synthesis of α,β-Disubstituted Enamides
作者:Lucas L. Baldassari、Aurélien de la Torre、Jing Li、Diogo S. Lüdtke、Nuno Maulide
DOI:10.1002/anie.201709128
日期:2017.12.4
Activate first, attack later: Thanks to an ynamide preactivation strategy, otherwise incompatible reagents can be used to prepare α,β-disubstituted enamides with high regio- and stereoselectivity. Mechanistic analysis reveals the intermediacy of a triflate-bound species as a solution-stable, effective keteniminium reservoir, which is amenable to the subsequent addition of organometallic reagents.
With Et3N·3HF as the fluorinating reagent, a copper(I)- or silver(I)-catalyzed β/α-site-regiocontrolled trans-hydrofluorination of alkynamides has been achieved, affording the corresponding fluoro enamides in moderate to nearly quantitative yields with high regio- and stereoselectivity, respectively. The reaction proceeds under mild reaction conditions and exhibits good functional group tolerance.
Copper-Catalyzed Alkynylation of Amides with Potassium Alkynyltrifluoroborates: A Room-Temperature, Base-Free Synthesis of Ynamides
作者:Kévin Jouvin、François Couty、Gwilherm Evano
DOI:10.1021/ol101322k
日期:2010.7.16
An efficient copper-mediated method for the coupling of potassium alkynyltrifluoroborates with nitrogen nucleophiles is reported. This reaction provides the first base-free and room-temperature synthesis of ynamides and allows for an easy preparation of these useful building blocks.