Oximes deoxygenation

Oxime deoxygenation by titanium(III) chloride spurred investigation of this agent for reducing nitro aliphatics the method is applicable to other nitro compounds. - The active species are thought to be ArN02H and a hydrolyzed form of titanium(II). The reaction conditions have been optimized for the reduction of aromatic and even heteroaromatic nitro compounds. ... 

Deoxygenation of Cyclic Nitronates Since cyclic nitronates are readily available and are rather stable compounds (see Sections 3.2 and 3.3), simple approaches for their deoxygenation with retention of the configuration of stereocenters can be used for the synthesis of cyclic esters of functionalized oximes. 

Tertiary amine TV-oxides are rapidly deoxygenated by carbon disulphide1112. Oximes are reduced to primary amines by titanium(III) chloride in the presence of sodium cyanoborohydride, NaBTpCN1. The combined action of sodium borohydride and a chiral... 

Stannous chloride is used most frequently for the reduction of nitro compounds [177, 178, 179] and of quinones [180, 181], It is also suitable for conversion of imidoyl chlorides [182] and of nitriles [183] to aldehydes, for transformations of diazonium salts to hydrazines [184], for reduction of oximes [f[Pg.30]

Deoxygenation of sulfoxides, selenoxides, oximes, and nitroalkanes.2 The reduction of sulfoxides and selenoxides is possible with PI3 or P2I4 in CH2C.l2 even at temperatures of —78°. Yields are 70-95%. 

The utility of the method depends on the availability of the dioxime precursors. When the parent quinone is readily accessible, direct oximation provides a straightforward approach which has been used for the acenaphtho- and phenanthro-furazans, (22) and (94 n= 0), although in the former case mild conditions (SOCl2, 20 °C) are required for the subsequent cyclodehydration in order to avoid fragmentation of the product (73JOC1054) (see Section 4.22.3.1.1). o-Quinone dioximes can be generated by reduction of benzo-furoxans, but in many such cases direct deoxygenation to the benzofurazan is also possible. 

B. Carbon Monoxide-Mediated Deoxygenation of Oximes and Nitro Compounds... 

Naphthoquinone 1-oxime 1 reacts with guanidin-2-amine and similar compounds to yieldnaphtho[l,2-e][l,2,4]triazin-2-amine 1-oxides 2.132 Reaction of the oxime 1 with thiosemi-carbazides affords usually 2-anilinonaphtho[l,2-e][l,2,4]triazine 3 as deoxygenation products, and only in basic solution the corresponding 1-oxide 2 may be isolated.132... 

Ketimine radicals. Ketoximes are deoxygenated on treatment with sulfinyl chlorides via homolysis of the oxime sulfinates. When suppression of diradical recombination by steric hindrance is exploited, imine radical intermediates tend to undergo other reactions such as intramolecular addition. 

Deoxygenation. Nitroalkanes, nitrones, and heterocyclic (V-oxides submit their oxygen atoms to hexamethyldisilane. Nitroalkanes (via nitronate anions) are converted into oximes. ... 

Oxidative decarboxylations. See Decarboxylation Oxidative -elimination. See ( Elimination Oxidative sulfitolysis, 239-240. V-, P- and 5-Oxides deoxygenation, 115 Oximes Beckmann rearr., 136-137 heterocycles from, 307-308 reduction of, 98, 112 Oxirane (ethylene oxide) ... 

Reactions with Nitro and Nitroso Compounds. Primary ni-tro derivatives react with TMS-I to form the oximino intermediate via deoxygenation, which then undergoes dehydration as discussed for the oximes (eq 38). Secondary nitro compounds afford the silyl oxime ethers, and tertiary nitro compounds afford the corresponding iodide. Nitroalkenes, however, react with TMS-I at 0 °C to afford the ketone as the major product (eq 39). ... 

Thus in this case the catalytic reaction involves the anionic -form o f the nitroalkaneI which in general undergoes reactions at the metal centre di-f-ferent than those observed with the nitro derivatives in their neutral -form (3.2.) However it is interesting to point out the similarity between the probable intermediate formed during the deoxygenation reactions o-f nitro compounds by carbon monoxide <3.2.1.), and the intermediate which should lead to the oxime in the copper-catalysed reactions ... 

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