title: Development of palladium-catalyzed transformations using propargylic compounds.
abstract: It is known that propargylic compounds having an ester and a halide at the propargylic positions react with palladium complexes leading to π-propargylpalladium and allenylpalladium complexes, which cause various transformations in the presence of the reactants. The aim of the present study was to develop novel palladium-catalyzed transformations using propargylic compounds. As diastereoselective reactions of propargylic compounds with bis-nucleophiles, we have developed palladium-catalyzed reactions of propargylic carbonates with 2-substituted cyclohexane-1,3-diones, 2-(2-hydroxyphenyl)acetates and 2-oxocyclohex-3-enecarboxylates. These processes produce highly substituted cyclic compounds in a highly stereoselective manner. Through our studies on the construction of substituted 2,3-allenols by the reactions of propargylic oxiranes, it has been made clear that palladium-catalyzed coupling reactions occur in the presence of arylboronic acids and terminal alkynes. The processes can be carried out in mild conditions to yield substituted 4-aryl-2,3-allenols in a diastereoselective manner. In our attempt to develop CO2-recycling reactions, we developed a methodology for the synthesis of cyclic carbonates by palladium-catalyzed reactions of propargylic carbonates with phenols. Our findings suggested that the process proceeds through a pathway involving decarboxylation-followed fixation of the liberated CO2. Diastereoselective, enantioselective, and enantiospecific construction of cyclic carbonates have been achieved by the application of this methodology.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokushima, Tokushima, Japan. yoshida@ph.tokushima-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yoshida
mesh_terms: D000480:Alkynes / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry*; D002384:Catalysis; D003653:Decarboxylation; D005027:Ethylene Oxide / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D019800:Phenol / Q000737:chemistry; D020005:Propanols / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D002254:Carbonates; D020005:Propanols; D002245:Carbon Dioxide; D019800:Phenol; D010165:Palladium; D005027:Ethylene Oxide