Wojciech Szczepankiewicz

Synthesis of 4-Arylaminoquinazolines and 2-Aryl-4-arylaminoquinazolines from 2-Aminobenzonitrile, Anilines and Formic Acid or Benzaldehydes

Abstract 2-Aminobenzonitrile treated with anilines in the presence of aluminium chloride gave respective 2-amino-N-arylbenzamidines. 4-Arylaminoquinazolines lacking a substituent at the 2 position were obtained directly by heating 2-amino-N-arylbenzamidines in formic acid; in similar conditions other carboxylic acids did not react with the amidines. The latter when treated with aldehydes afforded 2-aryl-4-arylimino-1H-2,3-dihydroquinazolines readily oxidizable by potassium permanganate to 2-aryl-4-arylaminoquinazolines.

Highly selective synthesis of (E)-N-aryl-N-(1-propenyl) ethanamides via isomerization of N-allyl ethanamides catalyzed by ruthenium complexes

Abstract A convenient and highly selective method of synthesis of (E)-N-aryl-N-(1-propenyl)ethanamides via isomerization of respective N-allyl-N-arylethanamides catalyzed by [RuClH(CO)(PPh3)3] has been described. N-Allyl-N-arylethanamides have been obtained by allylation of respective N-arylethanamides under PTC conditions. It is proposed that the observed selectivity of the double bond migration to (E)-enamides is due to the interaction of the arene ring with the Ru atom in the transition state.

Synthesis of 4-arylaminoquinazolines via 2-amino-N-arylbenzamidines

Abstract A new synthesis of twelve 4-arylaminoquinazolines from 2-amino- N -arylbenzamidines and formic acid is described. The entering amidines were obtained in the reaction of anthranilonitrile with 50% molar excess of aromatic amines and anhydrous aluminium chloride.

Transformation of 5,5-diaryl-4,5-dihydro-1,2,4-oxadiazoles to 4-arylquinazolines

The transformation of 5,5-diaryl-4,5-dihydro-1,2,4-oxadiazoles to 4-arylquinazolines in boiling acetic anhydride via acyclic 1-acetyloxy-4-aryl-1,3-diaza-1,3-butadienes is described.

Synthesis of methyl esters of (2s or 2r) 2-(4-nitro-1-imiazolyl) alkanecarboxylic acids

Abstract 1,4-Dinitroimidazole (or its 2-methyl derivative) reacts with chiral a-amino esters and yields chiral esters of of 2-(4-nitro-1-imidazolyl)alkanecarboxylic acids.

Ortho Effects in the Dissociation of Ionized N-Chlorophenyl- and N-Bromophenyl-2-Aminobenzamidines: Intramolecular Aromatic Substitution with Cyclization to Protonated 2-(2-Aminophenyl)-1H-Benzimidazoles:

Electron ionization (70 eV) mass spectra, double-stage (MS2) 10 eV collision-induced dissociation (CID) product-ion mass spectra of molecular ions and triple-stage (MS3) sequential product-ion mass spectra of major fragment ions are reported for the parent N-phenyl and the isomeric ortho-, meta- and para-N-chlorophenyl- and N-bromophenyl-2-aminobenzamidines. Dissociation is greatly influenced by an ortho effect that favors the loss of ortho H atoms and particularly the loss of the ortho halogen substituents. Dissociation occurs via a two-step intramolecular aromatic substitution reaction and a distonic-ion intermediate inhibits scrambling of ring hydrogens thus favoring the loss of the ortho substituents. The ortho isomers form an abundant and diagnostic [M – X]+ fragment ion (X = Cl, Br) and are easily distinguished. Protonated 2-(1H-benzimidazol-2-yl)-phenylammonium ions are likely formed; they dissociate mainly by NH3 loss upon CID and react readily with pyridine by proton transfer.

Reactions of 1,4-dinitroimidazoles with hydrazines

Abstract Reaction of 2-methyl-1,4-dinitroimidazole with hydrazine results in expansion of the imidazole ring and formation of the 1,2,4-triazine derivative. Reaction of 1,4-dinitroimidazole with N-aminomorpholine yields 1-(N-morpholino)-4-nitroimidazole, by degenerative transformation of the imidazole ring. Treatment of 1,4-dinitroimidazoles with t-butoxycarbonylhydrazine results in the break down of the imidazole ring and formation of glyoxal dihydrazone derivatives. Structures of representative heterocyclic products were determined by X-ray analysis.

Synthesis of 2‐methyl‐4(5)‐nitro[15N1(3)]imidazole from 2‐methyl‐4(5)‐nitroimidazole

A simple four-stage conversion of 2-methyl-4(5)-nitroimidazole to 2-methyl-4(5)-nitro[ 15 N 1(3) ]imidazole is reported. The method consists in N-nitration of the initial compound to 2-methyl-1,4-dinitroimidazole, treating the latter with [ 15 N]glycine and N-dealkylation of the obtained (2-methyl-4-nitro[ 15 N 1 ]imidazol-1-yl)acetic acid through its bromination in the presence of phosphorus trichloride, followed by the hydrolysis of the non-isolated intermediate.