Palladium and Rhodium-Catalyzed Reactions for the Synthesis of γ, γ-Disubstituted Cyclohexenones and of some Trifluoromethylated Molecules

This thesis describes new applications of palladium and rhodium catalysis directed toward the synthesis of γ,γ-disubstituted cyclohexenones and of some trifluoromethylated molecules. The contents are divided in three chapters. Chapter 1 describes the development of a palladium-catalyzed α-arylation protocol applied to cyclic vinylogous esters to yield products that can be transformed in a one pot process to γ-alkyl, γ-aryl disubstituted cyclohexenones. The reaction was found to be generally high-yielding and displayed a broad scope with respect to both coupling partners. Chapter 2 describes a new class of redox isomerization of allylic alcohols that proceeds by desymmetrization of cyclohexa-2,5-dienols. The γ,γ-disubstituted cyclohexenone products were formed in high yield and the reaction was found to tolerate different functional groups. Mechanistic studies were performed and revealed some details about the course of the reaction, a formal 1,3-hydride shift. Chapter 3 contains two methods based on the palladium or rhodium-catalyzed addition of organoboron reagents to carbon-carbon or carbon-oxygen double bonds, applied to the synthesis of some trifluoromethylated molecules. In the first part, the palladium-catalyzed enantioselective addition of arylboroxines to trifluoromethylacetaldimines (or their N,O-acetals) is detailed. This process yields α-(trifluoromethyl)arylmethylamines which are useful building blocks in medicinal chemistry. The second part chronicles the development of a rhodium-catalyzed domino reaction for the enantioselective synthesis of a new class of small rings: (trifluoromethyl)cyclobutanols bearing an exocyclic double bond.Ph.D