Hydrazines, catalytic reduction

Many other examples are known of non-selective reactions of halo groups in pyridopyridazines with amines, alkoxides, sulfur nucleophiles such as hydrosulfide and thiolate ions, or thiourea, hydrazine(s), cyanide ion and dimethyl sulfoxide, or on catalytic reduction. 

To corroborate the proposed mechanism, the catalytic reductive aldol coupling of acrolein with phenyl glyoxal monohydrate was performed under 1 atmos. elemental deuterium. Exposure of the aldol product to excess hydrazine in situ results in formation of the pyridazine, which incorporates precisely one deuterium atom in a manner consistent with the general mechanism proposed in Scheme 22.4 (Scheme 22.9). 

The essential difference between the hydroxylamine reaction and the hydrazine reaction appears to be that silver nuclei are formed in the solution much more readily by hydrazine than by hydroxylamine. At sufficiently low pH and in the absence of copper, hydroxylamine does not readily form nuclei in the solution, and the catalytic reduction of the silver chloride occurs essentially at a solid interface with the silver nuclei. Hydrazine, on the other hand, readily forms nuclei in the solution and an important fraction of the total reaction involves the catalytic reduction of dissolved silver chloride. This would account for the well-known photographic properties of the two agents. Hydroxylamine is a cleanworking developer which, under proper conditions, yields little fog. Hydrazine shows much less selectivity and, although it develops an image, it also yields a relatively high fog density. 

The synthesis of a triptan with a chiral side chain begins by reduction of the carboxylic acid in chiral 4-nitrophenylalanine (15-1). The two-step procedure involves conversion of the acid to its ester by the acid chloride by successive reaction with thionyl chloride and then methanol. Treatment of the ester with sodium borohy-dride then afford the alanilol (15-2). Reaction of this last intermediate with phosgene closes the ring to afford the oxazolidone (15-3) the nitro group is then reduced to the aniline (15-4). The newly obtained amine is then converted to the hydrazine (15-5). Reaction of this product with the acetal from 3-chloropropionaldehyde followed by treatment of the hydrazone with acid affords the indole (15-6). The terminal halogen on the side chain is then replaced by an amine by successive displacement by means of sodium azide followed by catalytic reduction of the azide. The newly formed amine is then methylated by reductive alkylation with formaldehyde in the presence of sodium cyanoborohydride to afford zolmitriptan (15-7) [15]. 

Azoxypropane. (H3C)2-CH-(N20) CH-(CH3)2 col liq, bp 38° at 14 mm Hg. It was prepd by oxidg 2-azopropane as described for 1-azopropane. Catalytic reduction of 2,2 -azoxypropane produced N,N -di-2-propyl-hydrazine and with hot HC1 the compd was converted into hydrazine hydrochloride. The UV and IR spectra were repotted... 

Catalytic reduction of the 2-nitrophenyIhydrazones (745) and subsequent air oxidation of the tetrahydro-l,2,4-benzotriazines (746) which are formed is used for the synthesis of 3,4-dihydro-1,2,4-benzotriazines (747) (80FES715). In another cyclization of an o-nitro group, which somewhat resembles others (e.g. 736 —> 737) described earlier, treatment of l,l-dialkyl-2-(2-nitrophenyl)hydrazines (748) with acids affords 2-alkyl-1,2,4-benzotriazinium salts (749) (77JCS(P1)478). The 2-nitrophenylbromohydrazone (750) with sodium ethoxide and ethyl cyanoacetate forms 6-bromo-3-phenyl-l,2,4-benzotriazine (751) a mechanism for this interesting transformation, in which the cyanoacetate plays no part, has been proposed (79JHC33). 

Dibromobenzo[6]thiophene and its 6-carboxylic acid undergo bisdehalogenation on treatment with sodium hydrazide and hydrazine 515 and on catalytic reduction in alkaline solution,77 respectively. Bromonitrobenzo[6]thiophenes readily undergo debromination on treatment with copper and quinoline,412 copper bronze and benzoic acid,84 or tin and hydrochloric acid.516... 

Attempts to synthesize C-terminal peptide aldehydes using other reductive techniques are less successful. 24"29 The reduction of a-amino acid esters with sodium amalgam and lithium aluminum hydride reduction of tosylated a-aminoacyldimethylpyrazoles resulted in poor yields. 26,29 The Rosemond reduction of TV-phthaloyl amino acid chlorides is inconvenient because the aldehyde is sensitive to hydrazine hydrate that is used to remove the phthaloyl group. 27 28 jV -Z-Protected a-aminoacylimidazoles, which are reduced to the corresponding aldehydes using lithium aluminum hydride, are extremely moisture sensitive and readily decomposed. 25 The catalytic reduction of mixed carbonic/carboxylic acid anhydrides, prepared from acylated a-amino acids, leads to poor reproducibility and low yields. 24 The major problems associated with these techniques are overreduction, racemization, and poor yields. 

Phenylethylamine has been made by a number of reactions, many of which are unsuitable for preparative purposes. Only the most important methods, from a preparative point of view, are given here. The present method is adapted from that of Adkins,1 which in turn was based upon those of Mignonac,2 von Braun and coworkers,3 and Mailhe.4 Benzyl cyanide has been converted to the amine by catalytic reduction with palladium on charcoal,5 with palladium on barium sulfate,6 and with Adams catalyst 7 by chemical reduction with sodium and alcohol,8 and with zinc dust and mineral acids.9 Hydrocinnamic acid has been converted to the azide and thence by the Curtius rearrangement to /3-phenyl-ethylamine 10 also the Hofmann degradation of hydrocinnamide has been used successfully.11 /3-Nitrostyrene,12 phenylthioaceta-mide,13 and the benzoyl derivative of mandelonitrile 14 all yield /3-phenylethylamine upon reduction. The amine has also been prepared by cleavage of N- (/3-phenylethyl) -phthalimide 15 with hydrazine by the Delepine synthesis from /3-phenylethyl iodide and hexamethylenetetramine 16 by the hydrolysis of the corre-... 

Studies on model polynuclear catalytic systems have confirmed that for the catalytic reduction of dinitrogen under mild conditions, it is necessary to use a polynuclear transition metal complex capable of donating four electrons to form the hydrazine derivative. 

Coucouvanis, D., Mosier, P.E. Malinak, S. Laughlin, L. Demadis, K.D. (1995) Catalytic reduction of hydrazine and acetylene to ammonia and ethylene and stoichiometric reduction of CN to ammonia and methane by Fe/M/S clusters (M =Mo, V) with structural features similar to those of the Fe/Mo/S site in nitrogenase, Plant Sci. Biotechnol. Agric. (Nitrogen Fixation Fundamentals and Applications) 27, 137-42. 

VFe3S4X3] (X = Cl, Br, and I), (Me4N)2[TpVFeS4Cl3], and (Me4N)[(NH3)-(bipy)Fe3S4Cl3]. A study of the catalytic reduction of hydrazine (a nitrogenase substrate) to ammonia in the presence of an external source of electrons and protons shows that the rate of reduction decreases as the number of labile solvent molecules coordinated to the V atom decreases but does not depend on the nature of the atom attached to the Fe atoms. 

Reduction of 68 with zinc dust and ammonia54 or, better, hydrazine and Raney nickel53,57,58 gave rise to the dihydro compounds (70). For the most part these dihydro compounds are easily oxidized but they can be converted into stable adducts such as 71.53,59 81 More strenuous treatment of 68 (R = Br or I) with hydrazine and Raney nickel gave rise to 2,2 -diaminodiphenylmethane.53 The same compound is obtained from catalytic reduction of 70 (R = H).58... 

This hydrazine is available by catalytic reduction of acetone azine. ... 

Many hydroxypyrazine A oxides have been A(-deoxygenated to pyrazines with a variety of reducing agents which include heating with hydrazine hydrate in alcohols hydriodic acid and red phosphorus in acetic or phosphoric acid iodine and red phosphorus in refluxing acetic acid phosphorus tribromide in ethyl acetate sodium dithionite catalytic reduction with hydrogen over Raney nickel dry distillation with copper-chromite catalyst and titanium trichloride in tetrahydrofuran at room temperature. 

Compound 10b has been treated with a solution of the nitrating mixture made from acetic anhydride and nitric acid in dioxane affording nitro derivative 10c, with not very high yields. The catalytic reduction of nitro derivative 10c, carried out with hydrazine in ethanol in the presence of palladium on calcium carbonate, affords compound lOd. The guanidino group at C-5 has be i introduced by reaction of compound lOd with ( anamide in solution of hydrochloric acid affording the objective molecule 10. 

This hydrazine is available by catalytic reduction of acetone azine.1 Protection of carboxylic acids.2 The reagent reacts with carboxylic acid derivatives (the acyl chloride or mixed anhydride) to give a monoacylhydrazide, RCON(CHMe2)-NH(CHMe2). The derivatives are stable to both acids and bases. They are reconverted into carboxylic acids by selective oxidation, preferably with lead tetraacetate. The new method of protection has been used for penicillins. 

Thus, the initial pseudo 0 -order rate constants of the catalytic reduction of a variety of substituted nitrobenzenes were determined applying a tenfold excess of hydrazine hydrate. 

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