Radical Cyclization of Trichloroacetamides: Synthesis of Lactams

Abstract

Trichloroacetamides can act as radical precursors to synthesize nitrogen-containing heterocycles in a variety of processes, mainly involving atom transfer radical cyclizations (ATRC), mediated by Cu(I) or Ru(II) catalysts, and the hydride reductive method, employing either Bu₃SnH or (Me₃Si)₃SiH, or recently NaBH₃CN. Additionally, amine-mediated single-electron transfer cyclizations, as well as radical processes promoted by Ni, Fe, Mn, Ti, and Ag, have been developed. 1 Introduction 2 Atom Transfer Radical Cyclizations (ATRC) 2.1 Copper-Mediated Reactions 2.2 Ruthenium(II)-Mediated Reactions 2.3 ATRC Promoted by Other Metals 3 Photocyclization Reactions 4 Reductive Cyclization via Single-Electron Transfer Processes 4.1 Ni/AcOH-Promoted Cyclizations 4.2 Titanocene(III)-Catalyzed Reactions 4.3 Silver Acetate Mediated Reactions 4.4 Amine-Mediated Single-Electron Transfer 5 Cyclization Involving M–H Hydrogen Atom Donors (M = Sn, Si, B) 5.1 Bu₃SnH-Mediated Reactions 5.2 (Me₃Si)₃SiH (TTMSS)-Mediated Reactions 5.3 Borohydride-Mediated Radical Cyclizations 6 Concluding Remarks