Studies on Ruthenium Complex-catalyzed Selective Carbon-carbon Bond Forming Reactions

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Ruthenium complex-catalyzed following novel carbon-carbon bond forming reactions, which are characteristic of ruthenium catalysts, were developed.(1) Novel catalytic allylation reactions utilizing nucleophilicity of (pi-ally)ruthenium intermediate: First, on the basis of our previous study on ruthenium complex-catalyzed allylation of aldehydes with allylic acetates, we succeeded in developing ruthenium complex-catalyzed dehydrogenative allylation of primary alcohols with allylic acetates, affording alpha,beta-unsaturated ketones selectively. Second, ruthenium complex-catalyzed coupling of1,3-dienes or allylic carbonates with acrylic compounds leading to the selective synthesis of 3,5-dienoic acid derivatives were explored. The stereochemistry of 5Z in 3,5-dienoic acid derivatives strongly suggests that the latter reaction proceeds via an anti(pi-allyl)ruthenium intermediate. Furthemore, when allylamines were treated with acrylic compounds in the presence of Ru(COD)(COT) catalyst, the b … More ond cleavage of allylic carbon-nitrogen bond did not occur and the cycloaddition products, cyclobutane-beta-aminocarboxylic acid derivatives, were obtained in up to 85% yield. This reaction can be rationalized in consideration of ruthenium-catalyzed isomerization of allylamines to the corresponding enamines, followed by cycloaddition with acrylic compounds.(2) Ruthenium complex-catalyzed novel carbon-carbon bond forming reactions via activations of acetylenes and vinyl halides: 2,4-Dienes were successfully prepared in high yields with high regioselectivity by ruthenium complex- catalyzed highly selective codimerization of acetylenes and activated alkenes. Taking into account the mechanism of our previously reported [2+2] cycloaddition of norbomenes and dimethyl acetylenedicarboxylate, the present reaction also involves a rutenacyclopentene intermediate. Furthermore, we developed ruthenium-catalyzed dehydrohalogenative coupling of vinyl halides with alkenes, affording the corresponding substituted dienes. Even the sp^2-carbon-chloride bond of beta-chlorostyrene is activated by this ruthenium catalyst system. Less