Unexpected Decarbonylation of Acylethynylpyrroles under the Action of Cyanomethyl Carbanion: A Robust Access to Ethynylpyrroles

It has been found that the addition of CH₂CN^- anion to the carbonyl group of acylethynylpyrroles, generated from acetonitrile and t-BuOK, results in the formation of acetylenic alcohols, which undergo unexpectedly easy (room temperature) decomposition to ethynylpyrroles and cyanomethylphenylketones (retro-Favorsky reaction). This finding allows a robust synthesis of ethynylpyrroles in up to 95% yields to be developed. Since acylethynylpyrroles became available, the strategy thus found makes ethynylpyrroles more accessible than earlier. The quantum-chemical calculations (B2PLYP/6-311G**//B3LYP/6-311G**+C-PCM/acetonitrile) confirm the thermodynamic preference of the decomposition of the intermediate acetylenic alcohols to free ethynylpyrroles rather than their potassium derivatives.

An efficient synthesis of furan-3(2H)-imine scaffold from alkynones

A novel efficient method to generate spiro furan-3(2H)-imine derivatives is established by the reaction between the α,β-unsaturated ketones and aniline derivatives. The reaction involves 1,4- addition of aniline followed by the subsequent intramolecular cyclization mediated by tertiary alcohol to produce the furan-3(2H)-imine. All the synthesized compounds are characterized using nuclear magnetic resonance and high-resolution mass spectrometry (HRMS).

Palladium-Catalyzed One-Pot Carbonylative Sonogashira Reaction Employing Formic acid as the CO Source

A convenient palladium-catalyzed carbonylative coupling of aryl iodides and terminal alkynes with formic acid as the CO precursor has been developed. A variety of alkynones were obtained in good yields in a one-pot manner for the first time.