Biomedical subjects
Publications and source records attributed to Sukbok Chang.
A three-dimensional networked osmium nanomaterial (N-Os) was prepared by a thermal decomposition of Os3(CO)12 within mesopores of MCM-48. The novel N-Os species shows high catalytic activity and excellent reusability in the oxidation reactions of unsaturated compounds under mild conditions.
An efficient cooperative catalyst system for the coupling of a wide range of organic electrophiles with chelated formate is reported to afford aryl and alkenyl esters by the simultaneous employment of Ru and Pd catalyst, in which ruthenium first promotes chelation-accelerated decarbonylation of formate to release CO and carbinol that are presumed to be transferred, still chelated to Ru, into Pd catalyst, which catalyzes alkoxycarbonylation of the organic electrophiles.
[reaction: see text] A heterogeneous ruthenium catalyst, easily prepared by adsorption of [RuCl(2)(p-cymene)](2) on activated carbon, exhibited a highly efficient and selective catalytic activity in various environmentally attractive transformations such as aerobic oxidation, hydrolytic oxidation, and dehydration processes with excellent recyclability.
An efficient and catalytic protocol of hydroesterification of alkenes has been developed without a need for CO atmosphere. With the introduction of the 2-pyridyl moiety as a chelating group in formate, Ru3(CO)12-catalyzed activation of the formyl C-H bond of formate and subsequent addition of the intermediate to alkenes proceeded with almost complete suppression of decarbonylation. Stereoselectivity of the produced one-carbon elongated esters was good to excellent for the formation of the linear adduct depending on the bulkiness of the alkenes used. This procedure could be readily applied to a variety of olefins such as terminal, internal, cyclic, bicyclic, vinyl ether, and conjugated enone systems with high efficiency and selectivity. It was also amenable to a solvent-free condition. On the basis of the chelation-driven C-H bond activation of formate, a putative mechanism of the Ru-catalyzed hydroesterification of 2-pyridylmethyl formate has been proposed.
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