Triruthenium dodecacarbonyl/triphenylphosphine catalyzed dehydrogenation of primary and secondary alcohols

Dehydrogenation of alcs. into aldehydes and ketones by Ru3(CO)12/PPh3 based homogeneous catalysis has been investigated as an alternative for the classical Oppenauer oxidn. Several catalytic systems have been screened in the Oppenauer-like oxidn. of alcs. A systematic study of various combinations of Ru3(CO)12, mono- and bidentate ligands and hydride acceptors was performed to enable dehydrogenation of primary alcs. to stop at the aldehyde stage. Among many H-acceptors screened, diphenylacetylene (tolane) proved the most suitable judged from its smooth redn. Electron rich and deficient analogs of tolane have been synthesized and, based on competition expts. between these H-acceptors, a tentative catalytic cycle for the Ru3(CO)12/PPh3-catalyzed dehydrogenations has been proposed. The crystal and mol. structures of a ruthenium-triphenylphosphine-tolane adduct [i.e., dicarbonyl[(2,3,4,5-h)-2,3,4,5-tetraphenyl-2,4-cyclopentadien-1-one](triphenylphosphine)ruthenium] were reported. [on SciFinder (R)]