Oxidative Desulfurization-Fluorination: A Facile Entry to a Wide Variety of Organofluorine Compounds Leading to Novel Liquid-Crystalline Materials

The oxidative desulfurization-fluorination reaction of organosulfur compounds using an N-haloimide and a fluoride source is demonstrated to be an effective and mild fluorination method that allows us to synthesize in high yields with high chemoselectivity various types of gem-difluoro compounds, trifluoromelhyl-substituted (hetero)-aromatics, trifluoromethyl ethers, and N-trifluoromethylanilines. Herein briefly summarized are the synthetic procedures as well as the scope and limitations of the reaction. The applicability of the reaction is demonstrated by the synthesis of a difluorinated glutamic acid and novel liquid-crystalline materials having an N-trifluoromethylamino, trifluoromethoxy, or 1,2-difluoroethylene group. The fluorine-containing liquid-crystalline materials are compared with the corresponding non-fluorinated materials in respect to phase transition behaviors and electro-optical properties and shown to be suitable for not only super twisted nematic (STN) but also for thin film transistor (TFT)-addressed liquid crystals displays. 1. Introduction 2. Fluorination Reactions 2.1 Fluorination of Sulfides and Thiols 2.2 Fluorination of Dithioacetals 2.5 Oxidative Desulfurization-Fluorination of Dithioester and Orthothioester 2.4 Synthesis of Trifluoromethyl Ethers from Dithiocarbonates 2.5 Oxidative Desulfurization-Fluorination of Thionesters and Thioncarbonates 2.6 Synthesis of Trifluoromethylamines from Dithiocarbamates 3. Synthesis and Electro-Optical Properties of Novel Fluorine-Containing Liquid Crystals 3.1 Synthesis and Electro-Optical Properties of N-Trifluoromethylamino-Substituted Liquid Crystals 3.2 Syntheses and Electro-Optical Properties of Liquid Crystals having Trifluoromethoxy Polar Functional Group 3.3 Synthesis and Properties of 3-Substituted Phenyl Trifluoromethyl Ethers 3.4 Synthesis and Electro-Optical Properties of Liquid Crystals with a vic-Difluoro-Olefinic Moiety.