Hydrogen diazo group replacement with

Diazonium compounds have been treated with a great variety of reducing agents, some of which have become incorporated into procedures for replacing the diazo group by hydrogen. The more important of these processes involve reduction by ... 

It has been demonstrated that the presence of chlorine or bromine in the nucleus facilitates replacement of the diazo group by hydrogen little or no ether formation occurs.26 Apparently iodine also favors the redudng action of alcohols, but this point has not been investigated carefully.26 27 No attempts to deaminate fluorinated amines are recorded. Representative of the effitiency with which ethanol reduces diazonium salts derived from halogenated amines are the deaminations of m-chloroaniline 26 (87% yield), of 2-bromo-4-methylaniline 28 (67% yield), of 2,4,6-tribfomoaniline 29 (ca. 80% yield), and of 2-carboxy-4-iodoaniline30 (ca. 45% yield) in the biphenyl series the deamination of VIII in 53% yield 31 may be dted. 

Finally, it is possible to replace the diazo group with a hydrogen. This is accomplished by reaction with sodium borohydride or hypophosphorous acid (H3P02) ... 

Diazotization of aminophenothiazines yields the expected results only when there is stabilization of the amino groups by suitable ring substituents. 3-Amino-lO-methylphenothiazine and 3-amino-lO-ethylphenothiazine-5,5-dioxide have been diazotized and coupled with hydroxy- and aminonaphthalenes. Diazo groups have only been successfully replaced by hydrogen and chlorine. Thus, Flory... 

The replacement of a diazo-group by hydrogen may be effected by other redudng agents. If, e.g., a diazo-compound is boiled with alcohol, the latter is converted into aldehyde, thus liberating two hydrogen atoms, by which the diazo-compound is reduced ... 

By boiling a diazo-compound with alcohol the reaction may take place in a different way at times the diazo-group is not replaced by hydrogen, but by the ethoxy (-OC2H5) group, thus giving rise to a phenol ether. 

In this way a nitro group is introduced into the ring in a position meta to the methyl radical. In order to obtain nitro-toluene from the nitrotoluidine formed in this way, the amino group present in the latter must be removed. This is accomplished by converting the amine into a diazo compound (513), and boiling the latter with alcohol, when the diazo group is replaced by hydrogen —... 

Alkylation describes the reaction where an active hydrogen is replaced with an alkyl group, for example, a methyl group. Most polar groups can be alkylated, and many reagents can be used, for example, alkyl halogenides, diazo alkanes, and N,N -dimethylformamide dialkyl acetal. An example of an alkylation is the formation of methyl esters of fatty acids by using methanolic BF3, where boron trifluoride (BF3) acts as a catalyst. 

When treated with hypophosphorus acid (H3PO2), the diazo group of an aiyldiazonium salt is replaced with a hydrogen atom ... 

The white crystalline diazoketone is dissolved in 10 ml of dry chloroform. Hydrogen chloride gas is bubbled slowly for 2 min into the solution that is cooled in ice. A spectrum of the product, 5-chloro-4-oxo-A -benzoxycarbonyl L-[5- C]norvaline-a-benzyl ester, should exhibit no diazo absorption. The chloroform is removed by flash evaporation and the residual material is suspended in 20 ml of 6 Af HCl and heated at 70° for 10 hr. The supernatant solution is decanted and replaced with 20 ml of 6 iV HCl, and the procedure is repeated until no insoluble material remains. The solutions are combined, and the products generated by removal of the protecting groups (benzyl alcohol, toluene) are removed by lyophilization the remaining colorless, moist powder may be dried under reduced pressure over PaO.-,. The net yield of L-2-amino-4-oxo-5-chloropentanoic acid hydrochloride is about 80% (49 mg, 0.24 mmole specific activity 1.16 Ci/mole). The chloroketone hydrochloride can be recrystallized from acetone-water to give the free base m.p. 151°-152° (dec.). 

Following their work on the synthesis of the parent compound 2,6-naphthyridine (105) (105). Taurins and Li reported their work in full (107) and at the same time reported a synthesis of the 4-methyl derivative 104, isolated by Harkiss and Swift (62). 4-Cyano-3-pyridyl-acetonitrile (275) was methylated (CFLI-NaOQHs) in the side chain to afford 2-(4-cyano-3-pyridyl)propionitrile (276), which was treated with hydrogen bromide in ether to afford 3-amino-l-bromo-4-methyl-2,6-naphthyridine (277). Diazo-tization/bromination and replacement of the bromine groups with hydrazine gave 278, and reaction with CuS04 in acetic acid afforded 4-methyl-2,6-naphthyridine (98) (Scheme 23) (107), whose spectroscopic properties were identical with those reported previously (62,63). 

Other group examples are found in those with formaldehyde (p. 73), in diazo coupling (p. 77), in nitration (p. 80), and in the replacement of halogen by hydrogen (p. 75). The last reaction is of considerable interest its importance was first realized s when 2-bromo-4-ethoxycarbonyl-3,5-dimethylpyrrole in acetic acid was found to oxidize iodide to iodine, being converted into 3-ethoxycarbonyl-2,4-dimethylpyrrole very rapidly ... 

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