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The mechanism of silver-catalyzed hydroamidation of siloxy-alkynes reaction remains controversial. Using density functional theory (DFT), we revealed that the reaction takes place through a silylium ion migration mediated hydroamination (SMH) pathway. The SMH pathway goes through two steps, the first step is Ag+ promoted proton and silylium ion exchange between siloxy-alkynes and amide, leading to ketene and silyl-imines, the second step is Ag+ catalyzed nucleophilic addition between ketene and silyl-imines, following with a silylium ion migration afford the final product. In this reaction, Ag+ activates the siloxy-alkyne into silylium ion (TIPS+) and silver-ketene through the p–π conjugate effect, the silylium ion then catalyzes the reaction. According to our calculation, the scopes of alkynes in this reaction may be extended to silyl-substituted ynamines or silyl-substituted ynamides. The scopes of amide may be extended into the p–π conjugate system such as diazoles, diazepines, etc. Our calculations also reveal a concise way to construct enamides through Ag+ catalyzed nucleophilic addition between substituted-ketenes and silyl-substituted p–π conjugate system. Silver-catalyzed hydroamidation of siloxy-alkynes is a successful approach for the hydroamidation of internal alkynes, however the mechanism of this reaction is poorly understood. Here, the authors use density functional theory calculations to reveal that the reaction takes place through a silver activated silylium ion migration mediated hydroamidation pathway. [ABSTRACT FROM AUTHOR]

AlCl3 acts as a chlorinating agent for ynamides in the presence of stoichiometric amount of water in the environmentally benign solvent dimethylcarbonate, affording efficient access to (E)-α-chloroenamides via hydrochlorination, with water as a protic source. The role of water in the reaction was proven by deuterium labelling experiment. Epoxy-ynamides undergo iodochlorination in addition to the cleavage of the epoxy ring to afford (E/Z)-α-chloro-β-iodo-enamides. Regio- and stereochemical assignments for the products are based on X-ray crystallographic studies. Chloroenamides are formed regio- and stereo-specifically via hydrochlorination of ynamides with AlCl3+H2O (1:1) in a dimethyl carbonate; aryl substituted epoxy ynamides afford (iodo)(chloro) enamides upon treatment with ICl. [ABSTRACT FROM AUTHOR]

Sodium benzeneselenolate adds regio- and stereoselectively to 3-(trimethylsilyl)prop-2-yn-amides to give (Z)-3-(phenylselanyl)prop-2-enamides. [ABSTRACT FROM AUTHOR]

An efficient regio and stereoselective synthesis of functionalized E-vinyl ethers are described. The reaction could proceed via addition of primary alcohols and phenols to functionalized N-substituted 2-alkynamides which are produced via Ugi-4CR in the presence of triethylamine at room temperature. The reaction proceeds through sequential Ugi/nucleophilic reaction sequence. High yields, short reaction times, and simple operations are the advantages of this approach. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A tandem synthetic approach to previously unknown 3-aminoprop-2-enamides has been developed. It is based on Si-C desilylation of 3-trimethylsilylprop-2-ynamides and subsequent addition of an amine to the triple bond of intermediate terminal propynamides. The effects of the reaction conditions and amine nature on the efficiency of the process have been studied. [ABSTRACT FROM AUTHOR]