Asymmetric Synthesis of (αR)-Polyfluoroalkylated Prolinols Based on the Perfluoroalkyl-Induced Highly Stereoselective Reduction of Perfluoroalkyl N-Boc-pyrrolidyl Ketones

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.