Desoxybenzoins benzoins

An illustrative example of the Michael reaction is that of the thiirene dioxide 19b with either hydroxylamine or hydrazine to give desoxybenzoin oxime (87) and desoxybenzoin azine (88), respectively, in good yields6 (see equation 29). The results were interpreted in terms of an initial nucleophilic addition to the a, j8-unsaturated sulfone system, followed by loss of sulfur dioxide and tautomerization. Interestingly, the treatment of the corresponding thiirene oxide (18a) with hydroxylamine also afforded 86 (as well as the dioxime of benzoin), albeit in a lower yield, but apparently via the same mechanistic pathway6. 

The procedure described is essentially that of Ballard and Dehn.1 Stilbene has also been prepared by reduction of desoxy-benzoin,20 benzaldehyde,23 and benzil 2o-2c by dehydrogenation of ethyl benzene,30 toluene,30- 33- 3, and bibenzyl 33-3alkaline reduction of phenylnitromethane,40 phenylnitroacetonitrile,40 and desoxybenzoin 43 by distillation of benzyl sulfone,50 benzyl sulfide,60-63 calcium cinnamate,5 cinnamic acid,5d phenyl cinna-mate,6e-6/ and diphenyl fumarate ie by dehydrohalogenation of a,a -dichlorobibenzyl60 and benzyl chloride 63 by dehalogenation of a,a,c/,a -tetrachlorobibenzyl70 and benzal chloride 73 by the coupling of cinnamic acid and phenyldiazonium chloride 8 by de-... 

Tetraphenylcyclopentadienone has been prepared by the action of phenylmagnesium bromide on benzaldiphenylmaleide,1 and by reduction, dehydration, and oxidation of the methylene-desoxybenzoin obtained by condensing formaldehyde with desoxy-benzoin.2 The present procedure is essentially that of Dilthey.3... 

The known property of diorganyl tellurides of reducing metallic salts, applied to tita-nium(IV) chloride, generates a titanium(III) species which is a useful reagent for some selective reductions. By this method benzaldehyde is reduced to dihydrobenzoin, and benzyl to benzoin, and successively to desoxybenzoin. ... 

Desoxybenzoin has been prepared by treatment of bromo-stilbene with water in a sealed tube at 180-190° 1 by the reduction of benzoin 2 by the reduction of benzil 3 by the action of zinc and alcoholic hydrogen chloride on chlorobenzil 4 by the action of benzene on phenylacetic acid in the presence of phosphorus pentoxide 5 and by the action of benzene on phenylacetyl chloride in the presence of aluminum chloride.6... 

The alkylthio group in an aromatic ketone may be removed with Raney Ni without affecting the carbonyl group. Thus, treatment of desyl thioethers (a-alkylthiodesoxy-benzoins) with Raney Ni, which had been deactivated by refluxing in acetone,149 gave desoxybenzoins in yields of 55-90% (eq. 13.73).150... 

The reaction has been extended to other pinacols however, their preparation may involve lengthy procedures. Certain benzoins on reduction with metals and acids yield diols which are then converted to desoxybenzoins. These conversions involve the migration of a hydrogen atom rather than an alkyl group. Similarly, aromatic keto ethers and amino ketones have been prepared. 

Desoxybenzoins. Benzoins are reduced to desoxybenzoins by treatment with red phosphorus and iodine in carbon disulfide containing pyridine (3.5 hr., 25°). Presumably an a-iodo ketone is formed as an intermediate. This deoxygenation has been carried out also with hydriodic acid (1,449). 

Oxidation of benzoins to benzils Benzoins (1) are oxidized to benzils(2) in high yield by catalytic amounts of this lanthanide nitrate and 1 eq. of HCl in aqueous glyme. Benzil can also be obtained from desoxybenzoin and diphenyl-acetylene under these conditions. This oxidation has recently been reported with... 

Benzoin is oxidized by nitric acid to benzil, CeHs.CO.CO.CeHs. It is reduced by zinc and hydrochloric acid in alcoholic solution to desoxybenzoin, C6H5.CO.CH2.C6H5, by sodium amalgam to hydrobenzoin, C6H5.CHOH.CHOH.C6H5, and by hydriodic acid to dibenzyl, CeH5.CH2.CH2.C6H5. 

Oxy-3 methyl desoxybenzoin 8,183. 6-Oxy-3-methyl-desoxybenzoin 8 II 206. 2>Methy 1-benzoin 8 I 575. 

Replacement of hydrogen by acoxy groups s. 12, 218 13, 846 Benzoin acetates from desoxybenzoins s. 13, 225 H OAc... 

Desoxybenzoins from benzoins—Formazans from tetrazolium salts s. 14, 137... 

Another benzoin derivative, desoxybenzoin, undergoes a-scission with rather low quantum yields, too. However, it becomes an efficient initiator when utilized together with a hydrogen donor, such as tertiary amine or tetrahydrofuran. In this case, initiating radicals are generated by hydrogen abstraction with comparatively high yields [31,32] ... 

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