Effect of Brønsted acids on the thiophenol-mediated radical addition-translocation-cyclization process for the preparation of pyrrolidine derivatives.
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.
a Department of Chemistry and Biochemistry , University of Bern , Bern , Switzerland.
Valentin
V
Soulard
b CEISAM UMR 6230 - UFR des Sciences et des Techniques , Université de Nantes , Nantes, Cedex 3 , France.
Fabrice
F
Dénès
a Department of Chemistry and Biochemistry , University of Bern , Bern , Switzerland.
Philippe
P
Renaud
D003500:Cyclization; D005609:Free Radicals / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
D005609:Free Radicals; D010636:Phenols; D011759:Pyrrolidines; D013438:Sulfhydryl Compounds; C042983:thiophenol; C032519:pyrrolidine
C–H activation; Radical reaction; hydrogen atom transfer; propargylamines; pyrrolidines; thiyl radicals