Asymmetric Synthesis of (α<i>R</i>)-Polyfluoroalkylated Prolinols Based on the Perfluoroalkyl-Induced Highly Stereoselective Reduction of Perfluoroalkyl <i>N</i>-Boc-pyrrolidyl Ketones

Abstract

Reduction of the obtained chiral (S)- tert-butyl 2-(perfluoroalkanoyl)pyrrolidine-1-carboxylate with sodium borohydride or lithium aluminum hydride proceeded smoothly to give the corresponding (S)- tert-butyl 2-((R)-perfluoro-1-hydroxyalkyl)pyrrolidine-1-carboxylate in yields of 73-97% with excellent diastereoselectivities (up to >98% de), compared with the reduction of nonfluorinated (S)-tert-butyl 2-pentanoylpyrrolidine-1-carboxylate.