Silver-Mediated Organic Transformations of Propargylamines to Enones, α-Thioketones, and Isochromans

This work describes a series of silver-mediated transformations of propargylamines to provide diverse patterns of products, including enones, α-thioketones, and isochromans. A variety of enone derivatives were obtained by silver-catalyzed transformation of propargylamines with 3-chloroperoxybenzoic acid (m-CPBA) in aprotic solvent. In contrast, when the reactions were carried out in protic solvent with N-Boc-L-cysteine methyl ester (Boc = tert-butoxycarbonyl) as nucleophile, α-thioketones were obtained. Moreover, the first silver-mediated cascade cyclization of alkynyl alcohol-linked propargylamines giving isochroman scaffolds was also described in this paper.