4952-03-8Relevant articles and documents
Synthesis of Ethers via Reaction of Carbanions and Monoperoxyacetals
Kyasa, ShivaKumar,Meier, Rebecca N.,Pardini, Ruth A.,Truttmann, Tristan K.,Kuwata, Keith T.,Dussault, Patrick H.
, p. 12100 - 12114 (2016/01/09)
Although transfer of electrophilic alkoxyl ("RO+") from organic peroxides to organometallics offers a complement to traditional methods for etherification, application has been limited by constraints associated with peroxide reactivity and stability. We now demonstrate that readily prepared tetrahydropyranyl monoperoxyacetals react with sp3 and sp2 organolithium and organomagnesium reagents to furnish moderate to high yields of ethers. The method is successfully applied to the synthesis of alkyl, alkenyl, aryl, heteroaryl, and cyclopropyl ethers, mixed O,O-acetals, and S,S,O-orthoesters. In contrast to reactions of dialkyl and alkyl/silyl peroxides, the displacements of monoperoxyacetals provide no evidence for alkoxy radical intermediates. At the same time, the high yields observed for transfer of primary, secondary, or tertiary alkoxides, the latter involving attack on neopentyl oxygen, are inconsistent with an SN2 mechanism. Theoretical studies suggest a mechanism involving Lewis acid promoted insertion of organometallics into the O-O bond.
Crystalline MWW-type titanosilicate catalyst for producing oxidized compound, production process for the catalyst, and process for producing oxidized compound by using the catalyst
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, (2008/06/13)
A crystalline titanosilicate catalyst which is usable as a catalyst in the oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group, a process for producing the catalyst, and a process for producing an oxidized compound by an oxidation reaction using the catalyst. It has been found that a crystalline titanosilicate having a structural code of MWW effectively functions as a catalyst in an oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group, or a compound having a carbon-carbon double bond a functional group and having a total carbon number of not smaller than 2 and not larger than 5, wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent, thereby to highly selectively provide an intended oxidized compound.
Molybdenum-catalyzed epoxidations of oct-1-ene and cyclohexene with organic hydroperoxides: Steric effects of the alkyl substituents of the hydroperoxide on the reaction rate
Lempers,Van Crey,Sheldon
, p. 542 - 546 (2007/10/03)
A kinetic study of the epoxidation of oct-1-ene and cyclohexene with alkyl hydroperoxides is reported. The alkyl hydroperoxides were obtained in a moderate to high purity from the corresponding alcohols by acid-catalyzed exchange with hydrogen peroxide. The reaction rates in pseudo first-order experiments of these olefins with various alkyl hydroperoxides strongly depend on the structure of the alkyl group of the alkyl hydroperoxide. When one of the methyl groups in tert-butyl hydroperoxide (TBHP, 4a) is substituted by an alkyl group, R, the reaction rate decreases in the order Et > Pr > Bu > t BuCH2 > tBu. Substitution of two methyl groups of TBHP as in 1-ethyl-1-methylpropyl hydroperoxide (5a) and 1-ethyl-1-methylbutyl hydroperoxide (5b) showed a further decrease in reaction rate of epoxidation. When all three methyl groups are substituted by, for example, three ethyl groups as in 1,1-diethylpropyl hydroperoxide (6a) a decrease of approximately 99% in reaction rate is observed. Introduction of a ring system in the hydroperoxide such as in cyclohexyl hydroperoxide (3), 1-methyl-cyclohexyl hydroperoxide (2) and pinane hydroperoxide (1) also showed a dramatic decrease in reaction rate of epoxidation. An investigation of relative rates of epoxidation in competition experiments of cyclohexene and hex-1-ene with 1-tert-butylcyclohexene with different alkyl hydroperoxides also showed them to depend on the structure of the alkyl group of the alkyl hydroperoxide. These results are rationalized on the basis of a mechanism involving nucleophilic attack of the olefin on an alkylperoxomolybdenum(VI) intermediate. Bulky substituents at the α-position in the alkyl hydroperoxide can seriously impede the approach of the olefin to the O-O bond.
