HFIP-Promoted Selective Hydroxyalkylation of Aniline Derivatives with Arylglyoxal Hydrates.

A HFIP-promoted highly selective hydroxyalkylation of aniline derivatives with arylglyoxal hydrates has been realized. The reaction produces various N,N-dialkylanilines and their derivatives with α-hydroxy carbonyl units in good to excellent yields under mild conditions. Furthermore, the synthetic potential of this method has been demonstrated by the facile synthesis of several structurally interesting molecules such as benzil, 1,2,4-triazine, quinoxaline, hydantoin, and 2-thiohydantoin with aromatic amine units.

Synthesis of gem-Difluoro-3,4-dihydro-2H-pyrans via a TfOH-Catalyzed [4 + 2] Annulation of Difluoroenoxysilanes with α-Cyano Chalcones.

Difluoroenoxysilane, a commonly used difluoroallylating reagent, has attracted considerable attention in recent years. However, its application in the annulation reaction for the construction of fluorinated heterocyclic compounds remains relatively limited. Presented here is the Brønsted acid-catalyzed efficient formal [4 + 2] annulation of difluoroenoxysilanes with α-cyano chalcones. The developed protocol demonstrates tolerance to various substituents under mild reaction conditions, providing a reliable approach to construct gem-difluoro-3,4-dihydro-2H-pyrans in good to excellent yields with high diastereoselectivities.