Recent Developments in Trifluoromethylation or Difluoroalkylation by Use of Difluorinated Phosphonium Salts

Recent advances in trifluoromethylation or difluoroalkylation reactions by use of difluorinated phosphonium salts are summarized. In the presence of base, water, photocatalyst, fluoride or under the heating conditions, the difluorinated phosphonium salts can produce difluorocarbene, the CF2H radical or the trifluoromethyl anion, which are major intermediates for the difluoroalkylation or trifluoromethylation reaction and give moderate to excellent yields of the desired products in most cases. 1 Introduction 2 Difluoroalkylation of Alkenes and Imines 2.1 Bromo-/Oxydifluoromethylation of Alkenes 2.2 Hydrodifluoromethylation of Alkenes and Imides 2.3 Difluorocyclopropanation of Alkenes 3 Trifluoromethylation or Difluoroalkylation of Alkynes 3.1 Trifluoromethylation of Terminal Alkynes 3.2 Difluorocyclopropenation of Alkynes 4 Difluoroalkylation or Trifluoromethylation of Aldehydes and Ketones 4.1 Difluoroolefination of Aldehydes and Ketones 4.2 Hydroxydifluoromethylation of Aldehydes and Ketones 4.3 Trifluoromethylation of Aldehydes and Ketones 4.4 Trifluoromethylation of Indoline-2,3-diones for the Synthesis of 3-Fluoroalkenyl-3-trifluoromethyl- 2-oxindoles 5 Difluoroalkylation of Phenols, Thiols, Carboxylic Acids and Heterocyclic Amines 6 Trifluoromethylthiolation and Difluoroalkylation of Benzyl Halides or Aliphatic Halides 6.1 Trifluoromethylthiolation of Benzyl Halides or Aliphatic Halides 6.2 Difluoroalkylation of Benzyl Bromides 7 Trifluoromethylation of Aromatic Iodides 8 Difluoroalkylation of Diazo Compounds 9 Conclusion