Triflic Acid-Catalyzed Dehydrative Amination of 2-Arylethanols with Weak N-Nucleophiles in Hexafluoroisopropanol.

The catalytic deoxyamination of readily available 2-arylethanols offers an appealing, simple, and straightforward means of accessing β-(hetero)arylethylamines of biological interest. Yet, it currently represents a great challenge to synthetic chemistry. In most cases, the alcohol has to be either pre-activated in situ or converted into a reactive carbonyl intermediate, limiting the substrate scope for some methods. Examples of direct dehydrative amination of 2-arylethanols are thus still scarce. Here, we describe a catalytic protocol based on the synergy of triflic acid and hexafluoroisopropanol, which enables the direct and stereospecific amination of a broad array of 2-arylethanols, and does not require any pre-activation of the alcohol. This approach yields high value-added products incorporating sulfonamide, amide, urea, and aniline functionalities. In addition, this approach was applied to the sulfidation of 2-arylethanols. Mechanistic experiments and DFT computations indicate the formation of phenonium ions as key intermediates in the reaction.