| Abstract
| - A silica gel-immobilized [(Me3tacn)RuIII(CF3COO)2(H2O)]CF3CO2 complex (1−SiO2, Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) was prepared by simple impregnation, and the catalyst wascharacterized by powdered X-ray diffraction, nitrogen adsorption/desorption, Raman, and diffusereflectance UV−vis spectroscopies. The supported Ru catalyst can effect facile oxidation of alcoholsby tert-butyl hydroperoxide (TBHP). Primary and secondary benzyl, allylic, and propargylic alcoholswere transformed to their corresponding aldehydes and ketones in excellent yields; no oxidation ofthe CC and C⋮C bonds was observed for the allylic and propargylic alcohol oxidations. Likewisealkene epoxidation by TBHP can be achieved by 1−SiO2; cycloalkenes such as norbornene andcyclooctene were oxidized to their exo-epoxides exclusively in excellent yields (>95%). The 1−SiO2catalyst can be recycled and reused for consecutive alcohol and alkene oxidations without significantloss of catalytic activity and selectivity; over 9000 turnovers have been attained for the oxidationof 1-phenyl-1-propanol to 1-phenyl-1-propanone. 4-Substituted phenols were oxidized by the “1 +TBHP” protocol to give exclusively ruthenium−catecholate complexes, which were characterizedby UV−vis and ESI-MS spectroscopies. No (tert-butyldioxy)cyclohexadienone and other radicalcoupling/overoxidation products were produced using the “1 + TBHP” protocol. The formation ofruthenium−catecholate is proposed to proceed via ortho-hydroxylation of phenol.
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