Phenyl azide reduction

An attempt to improve the yield of the azepin-2-amine by the addition of sodium amide to the photolysate failed, as a rapid nonphotolytic reduction of the phenyl azide to aniline took place. 

The homobifunctional photoreactive BASED (Chapter 4, Section 5.1) has two photoreactive phenyl azide groups, each of which contains an activating hydroxyl. Radioiodination of this crosslinker can yield one or two iodine atoms on each ring, creating an intensely radioactive compound. Crosslinks formed between two interacting molecules are reversible by disulfide reduction, thus allowing traceability of both components of the conjugate. 

Figure 28.8 The heterobifunctional crosslinkers sulfo-SAND, SANPAH, and sulfo-SANPAH contain an amine-reactive (sulfo)NHS ester on one end and a photoreactive phenyl azide group on the other end. Sulfo-SAND allows release of conjugates by reduction of its internal disulfide bridge.

A number of by-products may be isolated from sodium stannite reductions. In addition to benzene, aniline gives phenol, azobenzene, phenyl azide, and phenylhydrazine.107 10 108 109 The danger of hydrolytic cleavage in alkaline media, previously discussed in connection with the... 

Interestingly, the reduction of phenyl azide (1) was not observed in these... 

Rates of reduction for the series of aryl azides studied are summarized in Table 3.8. It is evident that, for 3- and 4-substituents, the expected pattern of reactivity was observed, with electron-withdrawing substituents (Br, Cl and NO2) resulting in a much faster rate of reduction than for unsubstituted phenyl azide, which was in turn reduced more rapidly than those aryl azides bearing an electron-donating methoxy substituent. In order to obtain some quantitative measure of the contribution of these substituents to reaction rates, the results were modelled using the Hammett relationship [114], and the linear nature of the plot of log k against Hammett constant ([Pg.157]

Table 3.8. EFFECTS OF VARYING SUBSTITUENT ON THE RATE OF REDUCTION OF PHENYL AZIDES (RC H4Nj) BY DITHIOTHREITOL [113]...

Figure 3.6. Hammett plot for the reduction of substituted phenyl azides (RCfH4Nf by dithiothreitol. Data were taken from Table 3.8.

Gurtius and co-workers studied the acid-catalysed decomposition of alkyl azides such as benzyl azide. This was decomposed in either warm 1 1 (v/v) sulphuric acid-water or with concentrated hydrochloric acid to give a mixture of products corresponding to hydrogen migration [benzaldiinine (1)], phenyl migration [formaldehyde anil (2)], the azide reduction product [benzylamine (3)], and the solvolysis product [benzyl alcohol (4)]. The first two were obtained as the... 

The conversion of azides to mono substituted triazenes by reduction is a very difficult operation, owing to the instability of the products. Phenyltriazene (118) was prepared by the reduction of phenyl azide by stannous chloride in ether at —20° . 

The reduction in the yield of 2 at lower temperatures is not due to retardation of the rate of capture of diethyl amine by the electrophilic reactive intermediate. DeGraff et al. [26] found that there was no appreciable temperature dependence to the amine trapping reaction. Leyva et al. [69] confirmed this result (Table 3) but found that the yield of the 1/f-azirine intermediate is dramatically reduced upon laser flash photolysis of solutions of phenyl azide 1 and diethylamine in 2-MTHF. 

An especially promising approach lo the l,5-diaryl-l,2,3-triazoles was suggested some years ago, but apparently it has not yet been pursued. The addition of phenyl azide to -nitrostyrenes (Eq. 27) produces a poor yield of triazolines (2.2-13), but the subsequent reduction and elimination are essentially quantitative. 

Formation of 2-Trimethylsilylaziridines. The photochemical or thermal reaction of vinyltrimethylsilane with ethyl azido-formate or phenyl azide provides the trimethylsilylaziridine in modest yields (eq 22). Reduction of the formyl amide gives the parent trimethylsilylaziridine (eq 23). Trimethylsilylaziridines were also formed from the reaction of a-lithiochloromethyltri-methylsilane with imines, but this reaction only works with the imines of aldehydes. The reaction of bromotriazide, formed in situ from the reaction of bromine with sodium azide, with vinyl-silanes forms silylaziridines as well. This reaction was not carried out with vinyltrimethylsilane. However, vinyltriphenylsilane gave a 50% yield of 2-triphenylsilylaziridine under these conditions. 

Butyl alcohol in synthesis of phenyl 1-butyl ether, 46, 89 1-Butyl azidoacetate, 46, 47 hydrogenation of, 46, 47 1-Butyl chloroacetate, reaction with sodium azide, 46, 47 lre l-4-i-BUTYLCYCLOHEXANOL, 47,16 4-(-Butylcyclohexanonc, reduction with lithium aluminum hydride and aluminum chloride, 47, 17 1-Butyl hypochlorite, reaction with cy-clohexylamine, 46,17 l-Butylthiourea, 46, 72... 

Sodium, with l-bromo-3-chloro-cyclobutane to give bicyclo [l.l.O]butane, 51, 55 Sodium amalgam, 50, 50, 51 Sodium amide, with 2,4-pentane-dione and diphenyliodonium chloride to give l-phenyl-2, 4-pentanedione, 51, 128 Sodium azide, 50, 107 with mixed carboxylic-carbonic anhydrides, 51, 49 Sodium borohydride, reduction of erythro-3-methanesulfony-loxy-2-butyl cyclobutanecar-boxylate, 51, 12 reduction of 2-(1-phenylcyclo-pentyl)-4,4,6-trimethyl-5,6-dihydro-1,3(4H)-oxazine to 2-(1-phenylcyclopentyl)-4,4, 6-trimethyltetrahydro-l,3-oxazine, 51, 25 Sodium cyanoborohydride, used... 

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