Aerobic oxidation of organic compounds catalyzed by vanadium compounds

摘要

Aerobic oxidation of ot-hydroxy ketones catalyzed by dichloroethoxyoxovanadium in ethanol causes a carbon-carbon bond cleavage that produces diesters or diketones. This reaction is highly chemose-lective, and disecondary glycols do not react at all. However, ditertiary glycols effectively react with dichloroethoxyoxovanadium or trichlorooxovanadium to provide the corresponding ketones. Aerobic oxidation of a-hydroxy ketones catalyzed by dichloroethoxyoxovanadium or trichlorooxovanadium in aprotic solvents almost quantitatively affords the corresponding a-diketones. The reaction of tertiary cyclopropanol compounds with vanadyl acetylacetonate under an oxygen atmosphere causes fragmentation of the cyclopropane moiety to produce P-hydroxy ketones and p-diketones. For the 6-substituted bicyclo[4.1.0]heptanol derivatives, the endoperoxides are also obtained together with p-hydroxy ketones. Conversely, 2-ethoxycarbonylcyclopropyl silyl ethers produce 7-oxocarboxylate derivatives given the same reaction conditions. Monothioacetals are easily deprotected into carbonyls using a catalytic amount of trichlorooxovanadium in 2,2,2-trifluoroethanol under an oxygen atmosphere. Thiols are converted into the corresponding disulfides by the aerobic oxidation catalyzed by trichlorooxovanadium in the presence of molecular sieves 3A. Polymer-supported vanadium compounds are synthesized by the reaction of vanadium oxytrichloride with polymers bearing hydroxyl moieties. The catalyst prepared from TentaGel S OH was highly active and reusable for the aerobic oxidations.