David Robert Bryant

Organic selenoxides as oxidants in osmium tetroxide catalyzed oxidation of olefins to glycols

Abstract Olefins are catalytically oxidized to glycols by osmium tetroxide in the presence of organic selenoxide cooxidants. Glycols were obtained in good yields from mono-, di-, tri- and tetrasubstituted olefins.

Rhodium-catalyzed low pressure hydroformylation of vinyl esters: Solvent and phosphine effects on catalyst activity, selectivity and stability

Summary Rhodium/triarylphosphine complexes catalyze the low pressure ydroformylation of vinyl esters to α- and β-carbocypropionaldehydes. In contrast with hydrocarbon α-olefins, the branched aldehydes predominate, and the regioselectivity of the reaction is virtually unaffected by carbon monoxide partial pressure. Substrate steric effects and solvent effects are significant on both the reaction rates and linear/branched aldehyde selectivities. Rhodium-promoted hydrogenolysis of vinyl esters to ethylene and carboxylic acid is a major side reaction of this process. The results are rationalized in terms of the ability of the vinyl esters to form chelates.