Green and Practical Synthesis of Thioenamines and Chromones via Iodine-Catalyzed Cross-Dehydrogenation Coupling Reaction.

An iodine-catalyzed one-pot synthesis of thioenamines and chromones is reported. By using easily available phenyl isothiocyanate, alcohols, and enamines as starting materials, a tandem reaction (nucleophilic addition and the subsequent cross-dehydrogenation coupling) proceeded smoothly to give the desired thioenamines in good to excellent yields. This protocol features simple operation, mild conditions, a broad substrate scope, good atomic economics, and no need to add extra reaction solvents, providing a practical and green route for the synthesis of thioenamines. In addition, this method can also prepare some representative chromones in moderate yields.

One-Pot Synthesis of Benzoazole-Substituted Thioenamines via a Cross Dehydrogenation Coupling (CDC) Reaction.

An iodine-catalyzed synthesis of benzoazole-substituted thioenamines in a one-pot manner was reported. Using 2-aminothiophenols (or 2-aminophenols or 1,2-phenylenediamines), tetramethylthiuram disulfide (TMTD), and enamines (mainly indoles) as starting materials, the target C(sp2)-S formation products (benzoazole-substituted thioenamines) could be furnished smoothly in good yields. The reaction might proceed through an electrophilic substitution pathway in a cross dehydrogenation coupling (CDC) manner. The protocol is metal-free and features easy performance, a one-pot manner, a good functional group tolerance, and good yields.