Imidazoles, synthesis from azides

Benzenediazonium fluoroborate, 2-carboxy-xanthone synthesis from, 3, 838 Benzenediazonium ions phenyl azide formation from, 5, 839 Benzenediazonium salts, o-(imidazol-l-yl)-intramolecular diazo coupling, 5, 404 Benzene-1,2-disulfonimides N-substituted reactions, 6, 930 Benzene episulfide formation, 7, 577 Benzeneimine... 

Aryl and heteroaryl nitrene insertion processes have also been employed in the synthesis of heterocycles. The azide 459, for example, is converted on irradiation into the imidazole 460,383 and dihydro-10-thiaisoalloxazines are obtained in good yield on photoelimination of nitrogen from 6-(2-azido-phenylthio)uracils.384... 

For nonsymmetrical bicyclic imidazoles, direct TV-alkylation (arylation or acylation) is problematic since site-selectivity is influenced by many subtle electronic effects. Thus, Curtius rearrangement-based syntheses have been used widely for the synthesis of differentiated TV-substituted thienoimidazoles (104), (106) from (acylamido)thiophene carbonyl azides (103), (105) (Equations (30) and (31)) <79JCR(S)96>. These intermediates are useful for the synthesis of angiotensin II antagonists (Equation (32)) <91EUP483683,92EUP520423>. 

Rearrangement of alkoxycarbonyl imidazole acryl azides in diphenyl ether at high temperatures afforded imidazo[l,5-c]pyrimidinone or imidazo[4,5-c]pyridinone derivatives <02TL5879>. Efficient synthesis of imidazopyridodiazepines from peri annulation in imidazo[l,2-a]pyridine has been described <02TL9119>. A convenient synthesis of 3,6-disubstituted-2-aminoimidazo[l, 2-a]pyridines has been published <02TL9051>. Novel 2,3-dihydroimidazo[2,l-h][l,3]oxazoles were prepared from intramolecular nucleophilic i/wo-substitution of 2-alkylsulfonylimidazoles <02S2691>. 4,4 -Bi-l//-imidazol-2-ones were efficiently synthesized from 5-amino-ot-imino-1 //-imidazole-4-acetonitriles and isocyanates <02JOC5546>. 

Anions derived from halogenated imidazoles are frequently utilized in the formation of (7-heteroatom bonds. Bromolithium exchange of 961 (Scheme 233) followed by azidation 962 and reduction leads to 2-aminoimidazole 963 (PMB = -methoxybenzyl) <2003H(60)583>. The Mg-imidazolide intermediate from I/Mg exchange of 964, PBB = -bromobenzyl) reacts with sulfur dioxide for the synthesis of sulfonamide 965 <2003TL6509>. 

Full details of the synthesis of adenine and imidazole nucleosides of d-mannofuranose from 2,3 5,6-di-O-isopropylidene-D-mannofuranosylamine have now appeared (see Vol. 11, p. 171). The same group has also synthesized the arabinofuranosyl 5-aminoimidazole-4-carboxylate (14) by condensation of 2,3,5-tri-O-benzyl a-D-arafemo-furanosyl chloride with the parent base followed by hydrogenation. 1,3-Dipolar cycloaddition of glycosyl azides to 1,4-naphthoquinone or 2-methyl-1,4-benzoquinone gave the nucleosides (15), (16), and (17), which were shown to exhibit some cytostatic activity... 

Xie Z, Deng J, Qiu Z, Li J, Zhu Q (2016) Copper-mediated C(rp )-H azidation with Me3 SiN3 synthesis of imidazoles from ketones and aldehydes. Chem Commun 52(38) 6467-6470... 

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