Nitrosation of sugar oximes : preparation of 2-glycosyl-1-hydroxydiazene-2-oxides
2005-12-23, Brand, Jörg, Huhn, Thomas, Groth, Ulrich, Jochims, Johannes
Oximes of glucose, xylose, lactose, fructose, and mannose have been prepared. Nitrosation of the oximes of glucose, xylose, and lactose with NaNO2/HCl afforded 2-(-glycopyranosyl)-1-hydroxydiazene-2-oxides, which were isolated as salts 13, 22, and 28. Nitrosation of fructose oxime 29 furnished fructose, whereas nitrosation of mannose oxime 30 with NaNO2/HCl afforded the 1-hydroxy-2-(-d-mannopyranosyl)diazene-2-oxide 32, from which the p-anisidinium salt 31 and the sodium salt 33 were prepared. However, nitrosation of 30 with isopentyl nitrite in aqueous solutions of CsOH or KOH resulted in the formation of the 2-(-D-mannofuranosyl)-1-hydroxydiazene-2-oxide salts 34 and 35, respectively. Methylation of the ammonium 2-(-D-glucopyranosyl)-1-hydroxydiazene-2-oxide 13 yielded the 1-methoxy compound, which was benzoylated to afford the tetra-O-benzoate 14 a, the structure of which was confirmed by X-ray diffraction analysis. From the glucose O-methyloximes 15 and 16 the N-methoxy-N-nitroso-2,3,4,6-tetra-O-acetyl--D-glucopyranosylamine 18 was prepared. The structure of this compound was confirmed by X-ray diffraction analysis. Treatment of acetobromoglucose with cupferron furnished the 1-(2,3,4,6-tetra-O-acetyl--D-glucopyranosyloxy)-2-phenyldiazene-2-oxide 20.
Synthesis of N-Acyliminium Salts by Reaction of Nitrilium Salts with Ketones
1996, Al-Talib, Mahmoud, Zaki, Magdi, Hehl, Sabine, Stumpf, Rüdiger, Fischer, Helmut, Jochims, Johannes
A new method for the preparation of N-acyliminium salts 3a-ab by reaction of nitrilium salts 1 with non-enolizable alkyl and aryl ketones 2 is described. Ketones without electron-releasing substituents react only with N-arylnitrilium salts 1. An X-ray structural analysis was carried out for the N-acyliminium salt 3j. From variable temperature NMR spectroscopy intramolecular conformational changes (essentially rotation around the iminium C=N double bond, coupled to rotation about the amide C-N single bond) of few compounds 3 were determined. The observed barriers to hindered rotation are compared with barriers calculated by the AM1 method.
On the Reaction of Nitrilium and N-Acylamidinium Salts with Oximes and Other Hetero Nucleophiles
1993, Glocker, Michael O., Shrestha-Davadi, Prativa Bade, Küchler-Krischun, Jonna, Hofmann, Josef, Fischer, Helmut, Jochims, Johannes
Nitrilium salts 2 add oximes 1 to form stable alkylideneaminooxy-substituted iminium salts 4. Compounds 4 have been postulated by Meerwein as intermediates of the Beckmann rearrangement of oximes. For (E)-4c an X-ray structural analysis is performed. Other intermediates of the Beckmann rearrangement are the N-acylamidinium salts 5, which are produced by the reaction of nitrilium salts with amides. As models for the transformation of 5 into amides, the end products of the Beckmann rearrangement, reactions of N-acylamidinium salts with nucleophiles, e.g. oximes, alcohols, water, amines, thiols, and benzophenone imine are studied.
N-acyliminium salts from the reaction of nitrilium salts with aldehydes
1991, Jochims, Johannes, Glocker, Michael O., Hofmann, Josef, Fischer, Helmut
The nitrilium hexachloroantimonates 2a,d,g,p react with aromatic aldehydes to give isolable N-acyliminium hexachloroantimonates 10a-m. The N-aroyliminium salts (10g-m) and acyliminium salts with an aliphatic N-acyl group (10a-f) are of remarkably different stability. Contrary to the N-aroyliminium salts, compounds 10a-f are unstable in solution, e. g. react immediately with acetonitrile. With excess of aldehyde 10n,o give insertion products of the probable structures 12a,b. For 10b,f X-ray structural analyses have been carried out. The N-acylcyanamidium hexachloroantimonate 2p reacts with aldehydes to give new classes of cyclic N-acyliminium salts 13a-f, and 14f, respectively.
On alkylideneamidosulfenyl chlorides and 1-Thia-2-azoniaallene salts
2002, Wirschun, Wolfgang G., Hitzler, Martin G., Jochims, Johannes, Groth, Ulrich
X-Ray-diffraction analysis of tBu2CNSCl (4b) revealed an almost linear CNS unit with an SN bond order of ca. 1.9 (Fig. 1), in agreement with the structure of a 1-thia-2-azoniaallene chloride. With SCl2 and SbCl5, compound 4b was transformed into the imidosulfurous dichloride 6 (Scheme 2). With morpholine, compounds 4b and 6 afforded the sulfenamide 7and the aminosulfonium salt 8, respectively. The (diarylmethylene)amidosulfenyl chlorides 4g,h,i reacted with SbCl5 to give SbCl salts of the 1,2-benzisothiazoles 9a,b,d, most likely via 1-thia-2-azoniaallene intermediates 2 (Scheme 3).
Some reactions of 1,3-Dichloro-2-azoniaallene Salts with heteronucleophiles
1995, Hamed, A., Sedeak, Mohamed, Ismail, Abd El-hamid, Stumpf, Rüdiger, Fischer, Helmut, Jochims, Johannes
1,3-Dichloro-2-azoniaallene hexachloroantimonates (1) reacted with H2S to give 1,2,4-dithiazolium salts 2. With hydrazines 1,2,4-triazolium salts (3, 4) were formed. 1,3-Dimethylurea, respectively 1,3-dimethylthiourea or ethyl allophanate, reacted with 1 to afford 2-oxo- or 2-thioxo-1,3,5-triazinium salts (5–7). With diphenylmethaneimines imino substituted 2-azoniaallene salts 8 were produced. From chloroacetonitrile dichloropyrimidines 9, and from the tricyanomethyl anion a hexatriene 10 and a triazine 11 could be prepared. The 1,5-dichloro substituted 2-azoniaallene salts 12 reacted as bifunctional electrophiles with nucleophiles such as benzophenone hydrazone or anilines, to furnish 1,3,5-triazinium salts 14. Against benzohydrazide the allene 12j behaved as trivalent electrophile giving the bicyclic 1,3,5-oxadiazinium salt 13j, the constitution of which has been secured by a crystal structural analysis. The vinyl-2-azoniaallene salt 1i cyclized on heating to the 1,3-thiazinium salts 16, 17. From 17 the triazinium salts 18 were prepared with alcohols.
On the Reaction of alpha,alpha-Dichlorocarbenium Ions with Isocyanates
1992, Jochims, Johannes, Troll, Carsten, Fischer, Helmut, Wang, Q., Hamed, A., Ismail, Abd El-hamid, Taha Abdel-Aal, M., Zeid, Ibrahim, Al-Talib, Mahmoud
Trichlormethanes 4 react with two equivalents of n-alkyl isocyanates R2-NCO in the presence of SbCl5 to furnish the 2,2-dichloro-5,6-dihydro-6-oxo2H-1,3,5-oxadiazinium salts (9). The structure of these heterocycles is confirmed by an X-ray analysis of 9d (R1 = ClC = CCl2, R2 = Et). p-Tolyl isocyanate is Friedel-Crafts alkylated by 4b in the presence of SbCl5. Subsequent ring closure affords the quinolinium salt 13, which is hydrolyzed to give inter alia the quinolone 16.
Cycloadditions of 1-aza-2-azoniaallene cations to isothiocyanates
1999, El-Gazzar, Abdel-Rahman B.A, Scholten, Kirsten, Guo, Yiping, Weißenbach, Kerstin, Hitzler, Martin, Roth, Gerhard, Fischer, Helmut, Jochims, Johannes
Isothiocyanates react as S-nucleophiles with 1-aza-2-azoniaallene salts 1 to give different types of 1,3,4-thiadiazolium salts (9, 11, 12) and 1,2,4-triazolium salts (10). Which product is formed, depends on the one hand on the ability of a substituent of the heteroallene salt 1 to undergo a [1,2] shift as a positively charged migrant (generalized Wagner–Meerwein rearrangement) or to act as a cationic leaving group, and on the other hand on Dimroth rearrangement of the initially formed thiadiazolium salt 8 to triazolium salts. The structures of the thiadiazolium salt 9c and the triazolium salt 10d were confirmed by X-ray structural analyses.
On the Reaction of 1-Aza-2-azoniaallene Salts with Carbodiimides
1993, Wang, Quanrui, Troll, Carsten, Fischer, Helmut, Jochims, Johannes, Amer, Atef
1-Aza-2-azoniaallene cations 3, prepared in situ from geminal (chloroalkyl)azo compounds 2, react with carbodiimides 4 to give 4,5-dihydro-5-imino-1H-1,2,4-triazolium salts 7. An X-ray structural analysis was carried out for 71. According to AM1 calculations the cycloaddition of carbodiimides to 1-aza-2-azoniaallene cations occurs in a nonconcerted manner via cyanamidium cations 5 as intermediates. Hetero-Wagner-Meerwein rearrangements of the primary cycloadducts 6 provide the final products 7.
Reactions of 1-Thia-3-azoniabutatriene Salts with Alcohols, Carbonyl Compounds, Diazoalkanes, Nitrile Oxides, Nitrones, Enamines, and Butadienes
1991, Lubberger, Hans-Jürgen, Müller, Edgar, Hofmann, Josef, Fischer, Helmut, Jochims, Johannes
1-Thia-3-azoniabutatriene salts 1 react with alcohols, carbonyl compounds, diazo alkanes, nitrile oxides, nitrones, enamines, and 1,3-butadienes in all cases at the C=S double bond to yield new types of 2-azoniaallene salts (3, 9a, b, 13a, b, 18, 22) and other imines (2, 20). An X-ray diffraction analysis for 9b, the reaction product of 1b with 9-diazofluorene, confirms the proposed constitution.