Grignard reaction with peroxides

Decomposition of azo compounds and peroxides provides the alkoxyamine by the nitroxide-trapping of the primary radicals [29]. The radicals produced by hydrogen abstraction with oxy radicals are also trapped by the nitroxide [242, 243]. In the photoreaction, alkoxyamines were isolated with high yields [244]. The reactions of Grignard reagents with nitroxides [215] and the coupling reaction of sodium nitroxides with bromo compounds [234,235] are also used. The hydrolysis of 56 followed by the reaction with acyl or alkyl halides afforded alkoxyamines with various functional groups,63 (Eq. 68) [245-251] ... 

In the initial discovery of the asymmetric synthesis of a-chloro boronic esters 3, the diastereomeric ratios of 3 were estimated by reaction with Grignard reagents to form secondary alkyl boronic esters 5 and deboronation with hydrogen peroxide to secondary alcohols of known absolute configuration and rotation40. 

Electrophilic hydroxylationReaction of this peroxide (1) with Grignard reagents affords the corresponding silyloxy derivatives in 70-90% yield. The reaction with vinyl Grignard reagents results in silyl enol ethers or a-silyloxy ketones. 

ACGIH TLV 0.1 ppm DOT CLASSIFICATION 2.2 Label Nonflammable Gas SAFETY PROFILE Mildly toxic by inhalation. Explosive reaction with Grignard reagents (e.g., phenylmagnesium bromide). Reacts with tetrafluorethylene + air to form explosive peroxides. When heated to decomposition it emits toxic fumes of F". 

Mild oxidation of 3-substituted quinoxalin-2-ones, formed by reaction of quinoxalin-2(l//)-ones and Grignard reagents, with potassium hexacyanoferrate(III) or hydrogen peroxide gives aromatic systems. ... 

Diethoxymethane (DEM), an acetal with solubility similar to etheric solvents, may be a good substitute forTHF and EtzO [14]. DEM has a low propensity to form peroxides and can be used for Grignard reactions and organolithium reactions. Methyl lithium is available as a solution in DEM, which is much safer than CH3Li solutions in Et20 [15]. 

The reaction of alkylntagnesium reagents with di-r-bulyl peroxide leads to alkyl /-butyl ether, /-buiyl alcohol, and disproportionation products of the alkyl [96). Mechanistic studies showed that the initial step is ET. This conclusion was i.a. based on a linear correlation of log rale with the oxidation potentials of the Grignard reagents. Reactions of peroxides are extremely sensitive to metal catalysis, but take place even when high-purity magnesium is used. 

Chemiluminescence is observed during the reactions of aryl Grignard reagents with oxygen 4650 or with aryl peroxides.4656 Analysis of the luminescence spectrum and e.s.r. data indicates that for the oxygen-induced reaction brominated biphenyls are the emitters, whereas in the peroxide case triphenylmethane is the luminescent species. 

The use of thienyl Grignard reagents, and more recently lithiated thiophenes, has been extensive and can be illustrated by citing formation of oxythiophenes, either by reaction of the former with f-butyl perbenzoate or the latter directly with bis(trimethylsilyl) peroxide or via the boronic acid, the synthesis of thiophene carboxylic acids by reaction of the organometallic with carbon dioxide, the synthesis of ketones, by reaction with a nitrile, or alcohols by reaction with aldehydes, by the reaction of 2-lithiothiophene with A -tosylaziridine, and by syntheses of thieno[3,2- ]thiophene and of dithieno[3,2- 2, 3 - /]thiophene. Some of these are illustrated below. 

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