Effect of Brønsted acids on the thiophenol-mediated radical addition–translocation–cyclization process for the preparation of pyrrolidine derivatives

Abstract

A thiophenol-mediated method for the conversion of propargylamines to pyrrolidines under acidic conditions is described. This cascade reaction involves addition of a thiyl radical to the terminal alkyne followed by a 1,5-hydrogen transfer (radical translocation) and a rapid cyclization affording the pyrrolidine ring. Our studies reveal that complete protonation of the tertiary amine with 10 equivalents of trifluoroacetic acid avoids undesired hydrogen atom abstractions by the thiyl radicals.

Keywords:

• Radical reaction
• hydrogen atom transfer
• C–H activation
• thiyl radicals
• propargylamines
• pyrrolidines

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The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.