1.3- Dithiole-2-azide

Lithium aluminum hydride reduced )J-azidoethylbenzene to j8-aminoethyl-benzene in 89% yield [600], The azido group was also reduced with aluminum amalgam (yields 71-86%) [149], with titanium trichloride (yields 54-83%) [601], with vanadous chloride (yields 70-95%) [217] Procedure 40, p. 215), with hydrogen sulfide (yield 90%) [247], with sodium hydrosulfite (yield 90%) [259], with hydrogen bromide in acetic acid (yields 84-97%) [232], and with 1,3-propanedithiol (yields 84-100%) [602]. Unsaturated azides were reduced to unsaturated amines with aluminum amalgam [149] and with 1,3-propane-dithiol [602]. 

It was concluded that dithiols should not be used in photoaffinity labeling experiments with aryl azides and monothiols should be used with caution. The reduction reaction can often be monitored spectrophotome-trically, e.g. 2-nitro-4-azidoanilines which are red-orange (Xmax 480 nm in H20) are converted to purple diamines (Xmax 550 nm). TLC and IR spectroscopy are also useful (Staros et al., 1978). 

While azides were far more susceptible to reduction by dithiols, the rates of reduction of a diazotrifluoropropionyl derivative by dithiothreitol, (3-mercaptoethanol, cysteine, and reduced glutathione did not differ widely. Thioglycolic acid was however a poor reductant and it was suggested that it should be used to replace (3-mercaptoethanol or DTT when diazo reagents are used. The reduction may be monitored by TLC or by a 500-fold increase in the absorbance at 260 nm. 

Dibenzo[l,2]dithiins 54 are prepared by oxidation of appropriate dithiols 53 and related starting materials (e.g., Scheme 27). Dibenzo[l,2]thiazine dioxide 56 is obtained by thermolysis of the azide 55 (Scheme 28) <1969JA1219>. 

The anion [OsNC14] can be obtained as its (Bu4N)+ salt by interaction of sodium azide solution.with an HC1 solution of potassium osmate. It reacts with maleonitrile dithiolate to give (Bu4N)2[OsN(mnt)2].115... 

Figure 3.5. Possible mechanism for the reduction of azides by dithiols.

The reaction of elemental sulfur in pyridine with 1,2-dithiolylium salts has been used for the synthesis of several l,2-dithiole-3-thiones.7 3-Chloro-1,2-dithiolylium salts give l,2-dithiole-3-thiones with sulfur-free bases such as ethanol, ammonia, methyl- and dimethylamine, piperidine, morpholine, and the azide ion.8 These salts form l,2-dithiol-3-ones with carboxylic acids.8... 

Substituted 1,3-dithiol-2-yl-azides, prepared from the 1,3-dithiolium salts, give on thermolysis the... 

Dithiolylium salts (66) give, on reaction with azide anion, 2-azido-l,3-dithioles (67) (Scheme... 

The dehydration of (/ )-2-hydroxyglutarate to glutaconate has been studied by Buckel and co-workers (229, 2S0), who have found that the syn elimination of ( )-2-hydroxyglutarate requires a prior activation of the enzyme from cell-free extracts of A. fermentans by ATP, NADH, and MgCl2. The enzymic reaction requires a dithiol, acetyl phosphate, and CoASH, as well as strictly anaerobic conditions, because the active enzyme is irreversibly inactivated on contact with oxygen. Evidence was presented that the adenylation of the protein may be a requisite for activation. Based on preliminary EPR studies and the inactivation of the enzymic reaction by hydroxylamine and uncouplers of oxidative phosphorylation (such as azide, arsenate, and 2,4-dinitrophenol), Schweiger and Buckel postulated a radical mechanism for 2-hydroxyglutarate dehydration via the hydroxyl radical (Scheme 53) (229). Hence, the ATP/NADH-dependent ac-... 

Vanadium(III) complexes, 473 adenine, 475 alcohols, 478 amides, 474, 480 amines, 474 amino acids, 484 ammonia, 474 aqua, 477 arsines, 476 azide, 475 bipyridyl, 475 bromides, 483 carboxylates, 479 catecholates, 478 chlorides, 482 complexones, 485 cyanides, 474,476 (Wethyl sulfoxide, 480 dioxygen, 478 dithiocarbamates, 481 dithiolates, 481 dithiophosphinates, 481 ethers, 478... 

A later-developed method to obtain amines from azides consists in their reduction with propane-1,3-dithiol,employing ethyldiisopropylamine as a base. The transformations reported proceeded rapidly and resulted in, 2-trans selectivity. Unverzagt described the reduction of the azido heptasaccharide 221 by this dithiol method, to give exclusively the p amine 222. In contrast, reduction of 221 by Raney nickel resulted in both anomers 222 and 223, with p a = 7 3. A corresponding reduction of the azido octasaccharide gave a 52% yield however, a low yield of 35% was observed in the reduction of the thio sugar azide 68 with propane-1,3-dithiol... 

An extensive study revealed that the A-dithiasuccinyl-protected azide 224 offers a major advantage in the synthesis of A-glycans. Efficient reduction of the A -dithiasuccinyl- and azido-functionality in 224 could be achieved, either in solution by utilizing simultaneous in situ reduction with Zn in THE AcOH AC2O, or on solid phase upon treatment with ethyldiisopropylamine and an excess of dithiothreitol, propane-1,3-dithiol, or 2-mercapto-A-methylacetamide leading to the known 1 or 225. 

Dihydro-l,4-dithiin-2,3-dithiolate Centrid Nitride Azide... 

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