Molybdenum hexacarbonyl ketones

Highly selective reduction of aldehydes rather than ketones, even 4-f-butylcyclohexanone, has been achieved by a binuclear hydrido molybdenum anion (Et4N[ JL-HMo2(CO)io]) and acetic acid in refluxing THF," The stable complex is readily prepared from molybdenum hexacarbonyl, which can be recovered after reduction. The full value of this reagent in synthesis remains to be established. Tributyltin hydride has been shown to be effective for the selective reduction of aldehydes in the presence of dried silica gel which acts as a mild acid catalyst," The reaction proceeded at room temperature in cyclohexane, many common functional groups were inert under these conditions. 

Molybdenum hexacarbonyl. 13. 194-1 Clea vage of isoxazoles. The m i Id < ketones without affecting alkene units p Cycloisomerization. Homoproparg... 

The action of molybdenum hexacarbonyl on the isoxazole ketones 5 (R = Me, Ph or n-hexyl) leads to the pyridones 6 with cleavage of the nitrogen-oxygen bond (94H853). The nitrenium ion 8 is produced by photolysis of 1-t-butyl-3,5-dimethyl-2,1-benzisoxazolium tetrafluoro-borate 7 (94TL4943). 

Reaction with activated halides. Molybdenum hexacarbonyl reacts with a-halo ketones (equimolar amounts) in refluxing DME as shown in equation (1). The... 

Nitroalkanes and nitrocycloalkanes are convertible to ketones by potassium tert-butoxide and tm-butyl hydroperoxide in the presence of molybdenum hexacarbonyl or vanadium oxyacetylacetonate (Bartlett et al, 1977). Ketone, acetal, and ester functions are unaffected. 

Diazonium salts also readily react with nickel carbonyl, yielding mainly carboxylic acids and ketones in the presence of water and hydrochloric add (26, 27). Iron pentacarbonyl and dicobalt octacarbonyl with diazonium salts behave similarly, but the hexacarbonyls of chromium and molybdenum are virtually ineffective. This reaction may be considered as a transition metal-catalyzed carbonylation of aryl radicals, and is closely related to the Meer-wein reaction (26). 

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