Imidazo[1,5-a]pyridines in acetic acid solution are readily nitrated by nitric acid–sulphuric acid, although in some instances treatment of the base hydrogensulphate with nitric acid–acetic acid is preferred. Nitration occurs most readily in the 1-position, but 3-nitration occurs if the 1-position is already substituted.

Die Nitrierung der Titelverbindungen erfolgt in essigsaurer Lösung mit HNO 3 ‐H2SO4.

Oxidation of 1-substituted 2-aminoimidazo[1,5-a]pyridinium salts with an excess of concentrated nitric acid gave the corresponding 2-pyridylmethylenecarbamic acid hydro-salts. Oxidation of 3-substituted -2-aminoimidazo[1,5-a]pyridinium bromide with nitric acid in acetic acid gave the corresponding 1-nitro-3-substituted imidazo[1,5-a]-pyridines. The parent 2-aminoimidazo[1,5-a] pyridinium bromide yielded either type of product depending upon the reaction conditions.Oxidation of 2-amino-1-phenylimidazo[1,5-a]pyridinium bromide with lead(IV) acetate in acetic acid solution gave 2-acetamido-3-oxo-1-phenyl-2,3-dihydroimidazo[1,5-a] pyridine.

AbstractDie Oxidation der Titelverbindungen (I) wird unter verschiedenen Bedingungen untersucht.

The title reactions afford, respectively, 1-acetamido-2-pyridone, 1-acetamido-2-quinolone, and 2-acetamido-1-isoquinolone. In the case of 1-amino-2-methyl- and 1-amino-4-methyl-pyridinium bromides, ring bromination accompanies oxidation, suggesting the involvement of the bromide ion in the oxidation process.

AbstractDie Titelverbindungen (I) werden von dem Reagenz (II) [z. T. in situ aus dem Hydroximsäureester (IV)] am N‐1 unter Bildung der Salze (III) [im Falle von (IIIc) Isolierung als Perchlorat] aminiert.

Imidazo[1,2-a]pyrimidines are N-aminated at N-1 by O-p-tolylsulphonylhydroxylamine. Subsequent oxidation of the resulting N-amino-salts with bromine generally results in the corresponding 1,1′-azoimidazo[1,2-a] pyrimidinium salts.

Treatment of 4-amino-6-methylpyrimidine with phenacyl bromide followed by base gives 3-amino-6-phenyl-pyrrolo[1,2-c]pyrimidine and not 7-methyl-2-phenylmidazo[1,2-c]pyrimidine as reported previously. Similar treatment of 4-amino-2-methyl- and 4-amino-2,6-dimethyl-pyrimidine yields 2-amino-7-phenyl- and 2-amino-4-methyl-7-phenyl-pyrrolo[1,2-a]pyrimidine, respectively.

N-Amination of imidazo[1,2-a]pyridines, pyrido[1,2-a]benzimidazole, s-triazolo[1,5-a]pyridines, and s-triazolo-[4,3-a]pyridines is described. 1-Amino-s-triazolo[1,5-a]pyridinium salts were also obtained by cyclizing 2-(2-acylhydrazino)-1-aminopyridinium salts. Oxidation of 10-aminopyrido[1,2-a]benzimidazolium bromide and 1-amino-s-triazolo[1,5-a]pyridinium salts with bromine gave 10,10′-azopyrido[1,2-a]benzimidazolium and 1,1′-azo-s-triazolo[1,5-a]pyridinium salts, respectively. Similar oxidation of 3-amino-2-methyl-1-phenylbenzimidazolium bromide and 1-amino-s-triazolo[4,3-a]pyridinium salts resulted in deamination.

AbstractDie bei der Aminierung der Imidazopyridine (Ia) und (Ib) mit O‐Tosyl‐ (oder O‐Mesyl‐) ‐hydroxylamin entstehenden Salze (II) werden durch Oxidation mit Brom in die Dihydroazetopyridiniumbromide (IIIa) bzw. (IIIb) übergeführt.

AbstractDie Umsetzung von 4‐Amino‐6‐methyl‐pyrimidin (II) mit Phenacylbromid und anschließend mit einer Base gibt nicht, wie berichtet wurde, das Imidazopyrimidin (I), sondern über das quaternäre Salz (III) das Pyrrolopyrimidin (IV).

Imidazo[1,5-a]pyridines are N-aminated by O-mesityl- or O-p-tolyl-sulphonylhydroxylamine and the resulting N-amino-compounds are converted by saturated aqueous bromine into brominated 1,2-dihydroazeto[1,2-a]pyridinium salts.

Aminierungen der Heterocyclen (I), (III), (V) bzw. (IX) mit Tosyl‐ (TSH) bzw. Mesitylensulfonylhydroxylamin (MSH) liefern die Salze (II), (IV), (VI) bzw. (X) [ im Falle von (Xb): durch nachfolgende Behandlung mit HBr]; analoge Behandlung der Heterocyclen (XI) gibt ein Gemisch der Salze (XII) (Hauptprodukte) und (XIII).

AbstractOxidation der Pyridylhydrazine (I) mit Brom gibt die Tetrazene′ (II); die Behandlung von (II) mit Methyljodid führt jedoch nicht zur erwarteten Ring‐N‐diquaternisierung, sondern zur Cyclisierung unter Bildung der Salze (IIIa); analoge Salze (IIIb) werden auch durch Cyclisierung von (II) mit HBr erhalten.

S. Anderson, E. E. Glover and K. D. Vaughan, J. Chem. Soc., Perkin Trans. 1, 1975, 1232 DOI: 10.1039/P19750001232

The preparation of 4H-thiazolo[2,3-c]-as-triazines from acetophenone thiazol-2-ylhydrazone and α-halogeno-ketones is described. Boiling concentrated hydrobromic acid failed to effect ring contraction of the 4H-thiazolotriazines to the corresponding 7-aminoimidazo[2,1-b]thiazolium salts. These last compounds were, however, prepared in high yield by treating the appropriate imidazo[2,1-b]thiazole bases with O-mesitylsulphonylhydroxylamine; oxidation of the 7-aminoimidazothiazolium salts with saturated aqueous bromine gave the title compounds.

AbstractDurch Cyclisierung des aus dem Amin (I) darstellbaren Thioharnstoffs (II) erhält man das Thiol (III), das sich mit H2O2 zu dem Disulfid (IV) oxidieren läßt, Die N‐Methylierung von (IV) gelingt nicht mit Methyljodid, wohl aber mit Methylfluorsulfonat.

The synthesis of 1,1′-dimethyl-4,4′-azo-1,2,4-triazolium salts, by oxidation of 4-amino-1,2,4-triazoles followed by quaternisation of the derived tetrazenes with methyl fluorosulphonate, is described. The azotriazolium salts were also obtained by oxidising the methobromides of 4-amino-1,2,4-triazoles with saturated aqueous bromine. No 1,1′-azobenzotriazole was isolated when 1-aminobenzotriazole was oxidised with acidified potassium bromate but the required title salts were obtained by oxidation of 1-aminobenzotriazole methobromide with saturated aqueous bromine.

Chemischer InformationsdienstVolume 5, Issue 43 Heterocyclic Compounds ChemInform Abstract: SYNTHESIS OF 1,1′-DIMETHYL-4,4′-AZO-1,2,4-TRIAZOLIUM AND 3,3′-DIMETHYL-1,1′-AZOBENZOTRIAZOLIUM SALTS EDWARD E. GLOVER, EDWARD E. GLOVERSearch for more papers by this authorKENNETH T. ROWBOTTOM, KENNETH T. ROWBOTTOMSearch for more papers by this author EDWARD E. GLOVER, EDWARD E. GLOVERSearch for more papers by this authorKENNETH T. ROWBOTTOM, KENNETH T. ROWBOTTOMSearch for more papers by this author First published: October 29, 1974 https://doi.org/10.1002/chin.197443232AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume5, Issue43October 29, 1974 RelatedInformation