Hydrazination reductions with

Sodium amide/hydrazine Reductions with sodium hydrazide/hydrazine NaNH IHsN NH ... 

V (Reduction with) ascorbic acid, hydrazine, or NH2OH HCl, CN , EDTA, F , H2O2, manni-... 

BrOg Reduction with arsenate(III), hydrazine, sulfite, or thiosulfate... 

Gravimetric methods more suitable for general use involve the precipitation of metallic gold from tetrachloraurate solutions by reduction with oxaUc acid, SO2, or hydroquinone. Formaldehyde, hydrazine, ferrous sulfate, and hypophosphorous acid also have been used but are considered less efficient (40). 

Several methods are available to supplement the phenol alkylations described above. Primary alkylphenols can be produced using the more traditional Friedel-Crafts reaction. Thus an -butylphenol can be synthesized direcdy from a butyl haUde, phenol, and mild Lewis acid catalyst. Alternatively, butyryl chloride can be used to acylate phenol producing a butyrophenone. Reduction with hydrazine (a Wolff-Kishner reduction) generates butylphenol. 

The compound can be prepared from 2,4,6-trinitrophenol (picric acid [88-89-1]) by reduction with sodium hydrosulfide (163), with ammonia —hydrogen sulfide followed by acetic acid neutralization of the ammonium salt (164), with ethanolic hydrazine and copper (165), or electrolyticaHy with vanadium sulfate in alcoholic sulfuric acid (159). Heating 4,6-dinitro-2-benzamidophenol in concentrated HQ. at 140°C also yields picramic acid (166). 

Other methods of generating a-aminoketones in situ are common, if somewhat less general than the methods already described. 2-Nitrovinylpyrrolidine, which is readily available, yields 2,3-bis(3-aminopropyl)pyrazine on reduction and this almost certainly involves ring opening of the intermediate enamine to an a-aminoketone which then dimerizes under the reaction conditions (Scheme 59) (78TL2217). Nitroethylene derivatives have also served as a-aminoketone precursors via ammonolysis of the derived epoxides at elevated temperatures (Scheme 60) (76S53). Condensation of 1,1-disubstituted hydrazine derivatives with a-nitro-/3-ethoxyethylene derivatives has been used in the synthesis of l,4-dialkylamino-l,4-dihydropyrazines (Scheme 61) (77S136). 

Few reactions of this type are recorded. The azidopyridazinone ester (349) on reduction with triethyl phosphite, hydrazine or borohydride furnished the pyrido[2,3-c]pyridazin-7-one (350) (79JHC1559), whilst an A-aminopyrido[2,3-c]pyridazine (352) resulted from the... 

Tropolone has been made from 1,2-cycloheptanedione by bromination and reduction, and by reaction with A -bromosuccinimide from cyolo-heptanone by bromination, hydrolysis, and reduction from diethyl pimelate by acyloin condensation and bromination from cyclo-heptatriene by permanganate oxidation from 3,5-dihydroxybenzoic acid by a multistep synthesis from 2,3-dimethoxybenzoic acid by a multistep synthesis from tropone by chlorination and hydrolysis, by amination with hydrazine and hydrolysis, or by photooxidation followed by reduction with thiourea from cyclopentadiene and tetra-fluoroethylene and from cyclopentadiene and dichloroketene. - ... 

Toluene from Toluidine.—It is often desirable to obtain tbe hydiocarbon from the base. The process of diazotisntion offers the only convenient method. The diazonium salt may be reduced by alcohol (Reaction 1, p. 162) or, as in the piesent instance, by sodium stannite. Less direct methods are the con-veision of the diazonium compound into (i) the hydrazine (see p. 174), (2) the acid and distillation with lime (p. 200), (3) the halogen derivative and reduction with sodium amalgam, 01, finally (4) the phenol and distillation with zinc dust. 

Catalytic hydrogenation of triple bonds and the reaction with DIBAL-H usually give the eis alkene (15-11). Most of the other methods of triple-bond reduction lead to the more thermodynamically stable trans alkene. However, this is not the case with the method involving hydrolysis of boranes or with the reductions with activated zinc, hydrazine, or NH2OSO3H, which also give the cis products. 

A molecular dissection of the alkaloid vasicine (52) ultimately resulted in the expectorant and mucolytic agent bromhexine (54). The synthesis starts with displacement of halogen on 2-nitrobenzyl-bromide (53) by N-methyl cyclohexylamine, followed by Raney nickel and hydrazine reduction of the nitro group. Bromination in acetic acid then affords bromhexine. 

Reduction with) ascorbic acid, hydrazine, or NH2OH HC1, CN-, EDTA, F-, H202, mannitol, oxidation to vanadate, triethanolamine, tiron Citrate, F-, H202, hydrazine, Na5P3O10, NH2OH HC1, oxalate, SCN-, tartrate, tiron, triphosphate, oxidation to tungstate(VI)... 

Moderate to good enantioselectivities were obtained for nearly all examples, but the products from 83a-c could be recrystallized to higher enantiomeric purity. Addition of iodine was critical for catalysis as was the use of a ligand with electron-poor para-fluorophenyl groups on the phosphorous atom. Substitution at the 3 position of the pyridine ring was described as being difficult for both the quinolines and pyridine systems. The resulting hydrazine derivatives could be easily converted to piperdines by reduction with Raney nickel or under Birch conditions. 

The procedure described is based on the selective reduction with diimide described by Ohno and Okamoto and by Nozaki and Noyori. It illustrates the generation of diimide from the air oxidation of hydrazine and the use of diimide for the selective reduction of the trans double bond in cis,trans,trans-, S,9-cyc o-dodecatriene, the product of trimerization of butadiene. ... 

Benzotellurepine has been prepared by the addition of Na2Te to o-diethynylbenzene in the presence of hydrazine hydrate, under PTC conditions. The compound is quite unstable but is converted into the more stable dihalides by treatment with SOjClj or Br2- The dihalides regenerate the tellurepine by reduction with NajS. ... 

More abundant are reductions with sodium sulfite which is applied in aqueous solutions (solubility 24%). Its specialties are reduction of peroxides to alcohols [257], of sulfonyl chlorides to sulfinic acids [252], of aromatic diazonium compounds to hydrazines [253], and partial reduction of geminal polyhalides [254] Procedure 43, p. 216). 

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