Enol

About: Enol is a research topic. Over the lifetime, 10643 publications have been published within this topic receiving 176170 citations. The topic is also known as: enols & Enol.

Frustrated Lewis pairs: metal-free hydrogen activation and more.

Abstract: Sterically encumbered Lewis acid and Lewis base combinations do not undergo the ubiquitous neutralization reaction to form "classical" Lewis acid/Lewis base adducts. Rather, both the unquenched Lewis acidity and basicity of such sterically "frustrated Lewis pairs (FLPs)" is available to carry out unusual reactions. Typical examples of frustrated Lewis pairs are inter- or intramolecular combinations of bulky phosphines or amines with strongly electrophilic RB(C(6)F(5))(2) components. Many examples of such frustrated Lewis pairs are able to cleave dihydrogen heterolytically. The resulting H(+)/H(-) pairs (stabilized for example, in the form of the respective phosphonium cation/hydridoborate anion salts) serve as active metal-free catalysts for the hydrogenation of, for example, bulky imines, enamines, or enol ethers. Frustrated Lewis pairs also react with alkenes, aldehydes, and a variety of other small molecules, including carbon dioxide, in cooperative three-component reactions, offering new strategies for synthetic chemistry.

Modern Fluoroorganic Chemistry: Synthesis, Reactivity, Applications

Abstract: PREFACE TO THE SECOND EDITION PREFACE TO THE FIRST EDITION INTRODUCTION Why Organofluorine Chemistry? History The Basic Materials The Unique Properties of Organofluorine Compounds PART I: Synthesis of Complex Organofluorine Compounds INTRODUCTION OF FLUORINE Perfluorination and Selective Direct Fluorination Electrochemical Fluorination (ECF) Nucleophilic Fluorination Synthesis and Reactivity of Fluoroaromatic Compounds Transformations of Functional Groups "Electrophilic" Fluorination PERFLUOROALKYLATION Radical Perfluoroalkylation Nucleophilic Perfluoroalkylation "Electrophilic" Perfluoroalkylation Difluorocarbene and Fluorinated Cyclopropanes SELECTED FLUORINATED STRUCTURES AND REACTION TYPES Difluoromethylation and Halodifluoromethylation The Perfluoroalkoxy Group The Perfluoroalkylthio Group and Sulfur-Based Super-Electron-Withdrawing Groups The Pentafluorosulfanyl Group and Related Structures THE CHEMISTRY OF HIGHLY FLUORINATED OLEFINS Fluorinated Polymethines Fluorinated Enol Ethers as Synthetic Building Blocks PART II: Fluorous Chemistry FLUOROUS CHEMISTRY Fluorous Biphase Catalysis FLUOROUS SYNTHESIS AND COMBINATORIAL CHEMISTRY Fluorous Synthesis Separation on Fluorous Stationary Phases Fluorous Concepts in Combinatorial Chemistry PART III: Applications of Organofluorine Compounds HALOFLUOROCARBONS, HYDROFLUOROCARBONS, AND RELATED COMPOUNDS Polymers and Lubricants Applications in the Electronics Industry Fluorinated Dyes Liquid Crystals for Active Matrix Liquid Crystal Displays Fluorine in Organic Electronics PHARMACEUTICALS AND OTHER BIOMEDICAL APPLICATIONS Why Fluorinated Pharmaceuticals? Lipophilicity and Substituent Effects Hydrogen Bonding and Electrostatic Interactions Stereoelectronic Effects and Conformation Metabolic Stabilization and Modulation of Reaction Centers Bioisosteric Mimicking Mechanism-Based "Suicide" Inhibition Fluorinated Radiopharmaceuticals Inhalation Anesthetics Blood Substitutes and Respiratory Fluids Contrast Media and Medical Diagnostics Agricultural Chemistry APPENDIX A: TYPICAL SYNTHETIC PROCEDURES Selective Direct Fluorination Hydrofluorination and Halofluorination Electrophilic Fluorination with F-TEDA - BF4 (Selectfluor) Fluorinations with DAST and BAST (Deoxofluor) Fluorination of a Carboxylic Acid with Sulfur Tetrafluoride Generation of a Trifluoromethoxy Group by Oxidative Fluorodesulfuration of a Xanthogenate Oxidative Alkoxydifluorodesulfuration of Dithianylium Salts Electrophilic Trifluoromethylation with Umemoto's Reagents Nucleophilic Trifluoromethylation with Me3SiCF3 Transition Metal-Mediated Aromatic Perfluoroalkylation Copper-Mediated Introduction of the Trifluoromethylthio Group Substitution Reactions on Fluoroolefins and Fluoroarenes Reactions with Difluoroenolates APPENDIX B: INDEX OF SYNTHETIC CONVERSIONS INDEX

New cross-aldol reactions. Reactions of silyl enol ethers with carbonyl compounds activated by titanium tetrachloride

Abstract: Synopsis: With the addition of titanium tetrachloride, silyl enol ethers can react with either aldehydes or ketones forming crossed aldol products. The carbonyl group of the aldehyde or ketone is activated by titanium tetrachloride, allowing for nucleophilic attack by a silyl enol ether at the carbonyl carbon (a titanium chelate forms as an intermediate). This addition reaction is dependent upon the metal salt, solvent, and temperature used. Critique: The fact that various reaction conditions were studied to find optimal reaction conditions that gave the highest yield of cross-aldol addition products strengthened the findings in this paper. Mukaiyama and coworkers concluded first that titanium chloride was best for this reaction compared to boron trifluoride etherate and stannic chloride. Secondly, it was observed that methylene chloride gave cross-aldol products in good yield while no reaction was observed in both diethyl ether and THF. Finally, reaction with aldehydes is favored at -78 o C while ketone reaction is favored at room temperature. It was also interesting to see that the use of unsymmetric ketones allows for regiospecific addition reactions at the olefinic position on the silyl enol ether.