Synthesis of Oxazoles Containing CF₃-Substituted Alcohol Unit via Tandem Cycloisomerization/Hydroxyalkylation from <i>N</i>-Propargylamides with Trifluoropyruvates

Abstract

Oxazoles are important five-membered heterocycles that contain both nitrogen and oxygen atoms. Due to their wide range of biological activities, many oxazoles demonstrate potential for extensive application in various fields, including medicinal chemistry. Trifluoromethyl carbinol, an important pharmacophore, contains both trifluoromethyl and hydroxyl groups and is common in molecules with important biological activities. Constructing oxazoles that contain a trifluoromethyl carbinol unit is undoubtedly important and valuable for expanding the chemical space in drug discovery. In this study, a simple and efficient method was developed for the synthesis of oxazoles containing a CF3-substituted alcohol unit via the tandem cycloisomerization/hydroxyalkylation of N-propargylamides with trifluoropyruvates through a rational Lewis acid catalytic mechanism. This Zn(OTf)2-catalyzed synthetic protocol is operationally simple and provides a series of oxazoles in moderate to good yields. The protocol demonstrates broad substrate scope, high functional group tolerance, and high atom economy and can achieve gram-level reactions, indicating the strong possibility of its practical application.

Keywords

• oxazole
• trifluoromethyl carbinol unit
• tandem reaction
• cycloisomerization
• hydroxyalkylation
• <i>N</i>-propargylamide