PREPARATION AND PROPERTIES OF HYDRIDE TRIPHENYL-PHOSPHINE RUTHENIUM COMPLEXES WITH 3-FORMYL (OR ACYL) PROPIONATE (R=H, CH3, C2H5; R'=H, CH3, C6H5) AND WITH 2-FORMYL (OR ACYL) BENZOATE (R'=H, CH3)

Article abstract of DOI:10.1016/S0022-328X(00)89230-X

Reactions of five-membered cyclic dicarboxylic anhydrides, such as phthalic anhydride and succinic anhydride, with RuH2(PPh3)4 give ruthenium complexes with 2-formyl benzoate and 3-formyl propionate , via the C-O bond cleavage of the anhydrides.Similar reactions of methylsuccinic anhydride or ethylsuccinic anhydride with RuH2(PPh3)4 afford mixtures of the isomer (R=CH3 or C2H5), in ca. 3 to 1 molar ratio in each reaction.Complexes with 2-acyl benzoate or 3-acyl propionate ligands formulated as or (R'=CH3, C6H5) are prepared from the reactions of corresponding 2-acyl benzoic or 3-acyl propionic acids with RuH2(PPh3)4.Upon contact with hydrogen at elevated pressure, or with hydrogen chloride or carbon monoxide at atmospheric pressure, these complexes release the corresponding γ-lactones, which are formed through the reduction of formyl or acyl groups in the carboxylate ligands followed by intramolecular condensations.Hydrogenation of 3-acyl propionic acids using ruthenium(II) complexes as catalyst gives γ-substituted γ-lactones in high yields.