ChemInform Abstract: CATALYTIC REACTIONS VIA Π‐ALLYLPALLADIUM COMPLEXES

Abstract

Various transformations of allylic esters and ethers via ir—allylic complexes catalyzed by palladium—phosphine complexes have been studied. Intramolecular reaction of a nucleophile offers a good synthetic method for five—membered ring ketones. Also nucleophiles reacted easily with ct—acetoxy—,y—unsaturated nitriles and 1,3—diene monoepoxides. It was found that the Carroll rearrangement is catalyzed by palladium complexes under mild conditions. Facile formation of conjugated dienes and terminal olefins from allylic esters and ethers has been studied. INTRODUCTION Palladium complexes catalyze numerous reactions (Ref.l). One important and unique group of reactions catalyzed by palladium complexes is the transformation of various allylic compounds. Especially allylic ethers and esters undergo various reactions smoothly in the presence of palladium—phosphine complexes as a catalyst. In the reaction of these allylic compounds, the first step is the oxidative addition of allylic compounds to Pd° species to form ir—allylpalladium complexes, which then undergo several transformations. In this paper, several transformations of various allylic compounds catalyzed by palladium complexes discovered in our laboratory are presented. REACTIONS OF NUCLEOPHILES The reaction of ¶-allylpalladium complexes with nucleophiles is a wellestablished reaction. Both stoichiometric and catalytic reactions are possible (Ref.2). Especially the reaction with carbon nucleophiles offers a good method for carbon—carbon bond formation. We have studied further synthetic applications of reactions of allylic compounds via ir-allylpalladium complexes. We have carried out studies aimed at preparing fiveand six-membered cyclic ketones by the palladium—catalyzed intramolecular reaction of active methylene with allyl phenyl ether moiety. We have synthesized methyl (E)-3-oxo-8phenoxy-6-octenoate (1) by the reaction of the dianion of methyl acetoacetate with (E)-l-chloro-4-pfienoxy-2-butene (77% yield), and carried out its cyclization using 5-10 mol% of Pd(OAc)2-piosphine or phosphite as a catalyst in various solvents without using a base (Ref.3). 0 CO2Me OPh 1 2Me eCO2Me + Pd(OAc)2 PPh3 2 —Pd(OAc)2 P T'°JCO2Me