Rhodium-Catalyzed Cascade Reactions of Dienynes Leading to Substituted Dihydronaphthalenes and Naphthalenes

摘要

The elimination of a number of reaction steps, the avoidance of toxic reagents, and the reduction of hazardous waste are important subjects in modern organic synthesis.To solve these problems, the development of novel cascade reactions, in which multiple reactions proceed in one step to afford complex molecules, is attractive. Obviously, the development of catalytic versions is even more attractive, and the use of a single multifunctional catalyst that is able to catalyze multiple fundamentally different transformations is ultimately desired. We recently reported cascade reactions catalyzed by a cationic rhodium(I)/dppf complex, including the olefin isomerization, the propargyl Claisen rearrangement, and the carbonyl migration reaction, which transform allyl propargyl ethers to allenic aldehydes and dien-als. In these cascade reactions, the single multifunctional cationic rhodium(I)/dppf catalyst sequentially activates the allylicand aldehyde C-H bonds, and the alkyne π bond.In the reaction of an enyne that possesses a phenyl-substituted alkene moiety, the corresponding dienal was obtained in high yield as a mixture of stereoisomers (Scheme 1).