Efficient Synthesis of New Tetracyclic Benzofuro[3,2-d]-imidazo[1,2-a] pyrimidine-2,5-(1 H,3 H)-diones

The aza‐Wittig reaction of iminophosphorane ( 1 ) with aromaic isocyanates gave carbodiimides ( 2 ), which were allowed to react further with (‐amino ester in the presence of a catalytic amount of sodium ethoxide to give selectively new tetracyclic benzofuro[3,2‐d]imidazo[1,2‐a]pyrimidine‐2,5‐(1H,3H)‐diones ( 5 ) in good yields. X‐ray structure analysis of 5i verified the proposed structure and the reaction selectivity.     

Synthesis of 3-Hetaryl-1,2,4,5-tetrahydropyrrolo[1,2-a]quinazoline-2,5-diones

A convenient method has been developed for the synthesis of 3-hetaryl-1,2,4,5-tetrahydropyrrolo[1,2-a]quinazoline-2,5-diones by the interaction of 4-chloro-2-hetaryl-3-oxobutyronitriles with substituted anthranilic acids.     

New synthesis of 6,7-dihydro[1,3]thiazolo[2,3-f]purine-2,4(1H,3H)-diones

Russian Journal of Organic Chemistry -     

Syntheses of optically active tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones and hexahydroimidazo[1,2-a]pyridin-2(3H)-ones

The reactions of (2S)-2-amino-2-substituted-N-(4-nitrophenyl)acetamides 16a-c, succindialdehyde (13), and benzotriazole afforded enantiopure (3S,5R,7aR)-5-(1H-1,2,3-benzotriazol-1-yl)-3-substituted-1-(4-nitrophenyl)tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones 17a-c, which were converted by sodium borohydride into (3S,7aR)-3-substituted-1-(4-nitrophenyl)tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones 18a-c. Chiral (2S)-2-amino-2-substituted-N-(4-methylphenyl)acetamides 12a-d, easily prepared in two steps from N-Boc-alpha-amino acids 10a-d, similarly reacted with glutaraldehyde (20) and benzotriazole to generate 5-benzotriazolyl-3-substituted-hexahydroimidazo[1,2-a]pyridin-2(3H)-ones 21a-d, which were converted by sodium borohydride directly into optically active 3-substituted-hexahydroimidazo[1,2-a]pyridin-2(3H)-ones 22a-d.     

Pyrrolo [1,2-a] [1,3,5] triazine-2,4(1H, 3H)-diones. III—Fragementation under electron-impact

The mass spectra of eight pyrrolo[1,2-a][1,3,5]triazie-2,4(1H, 3H)-diones have been examined. An unusual feature in the fragmentation of those compounds having a 7-alkoxycarbonyl function, namely loss of the whole ester grouping with concomitant hydrogen rearrangement, is discussed.     

Heterocycles. 10. A facile synthesis of 7-hydroxy-6,7-dihydro-5H-pyrrolo[1,2-a]imidazole

Reaction of imidazole with acrolein gave the title compound whose structure was confirmed by X-ray analysis.     

An efficient synthesis of 9H-pyrrolo[1,2-a]indoles

A novel and effective method has been developed for the synthesis of 9H-pyrrolo[1,2-a]indoles by treatment of 3-substituted-4,6-dimethoxyindoles with chalcones in the presence of hydrochloric acid.     

Electron ionization mass spectra of aryl- and benzyl-substituted 2,3-dihydroimidazo[1,2-a]pyrimidine-5,7(1H,6H)-diones

The electron ionization mass spectra of the 1-phenyl-, 1-benzyl- and 6-benzyl-1-phenyl-2,3-dihydroimidazo[1,2-a]pyrimidine-5,7(1H,6H)-dione derivatives were recorded at 70 eV to find out the effects of substituents on their fragmentations. Fragmentation pathways were studied using B/E and B(2)/E scans. Some fragmentations involved the loss of C(3)HO(2) or carbon suboxide. The possibility of keto-enol tautomerism was also studied. For comparison selected compounds were studied using (1)H and (13)C NMR spectroscopy to reveal the presence of possible tautomerism. Some ions including [M-OH](+) and [M-HCO](+) and NMR results indicate that the enol form is predominant both in the gas and in the liquid phase.     

2,3,5,8(1)-Tetrahydroimidazo[1,2-a]pyrimidine-2,5-dione derivatives

The corresponding ylidene, azomethine, and azo derivatives of 2,3,5,8(1)-tetrahydroimidazo [1,2-a]pyrimidine-2,5-dione were synthesized by reaction of 7-methyl-and 6-bromo-7-methyl-2,3,5,8(1)-tetrahydroimidazo[1,2-a]pyrimidine-2,5-diones with aldehydes, insatin, aromatic nitroso compounds, and arenediazonium salts. Ylidene derivatives of 7-methyl-2,3,5,8(1)-tetrahydroimidazo[1,2-a]pyrimidine-2,5-dione were also obtained by reaction of 2-amino-4-methyl-6-oxo-1,6-dihydro-1-pyrimidylacetic acid with carbonyl compounds.     

A novel synthesis of 3-(substituted)pyrimido[4,5-c]pyridazine-5,7(1H,6H)-diones

An improved synthesis of 3-(substituted)pyrimido[4,5-c]pyridazine-5,7(1H,6H)-diones, a known subclass of 4-deazatoxoflavins, is reported. The approach involves treatment of 3-methyl-6-(1-methylhydrazinyl)uracil with representative phenyl and alkyl glyoxal monohydrates, which in turn are obtained by selenium dioxide oxidation of the corresponding phenyl and alkyl methyl ketones. The first entry into 4-monosubstituted isomers is also reported.     

Pyrroloindoles. 6. New synthesis of 1H, 5H-pyrrolo[2,3-f]indole and 3H,6H-pyrrolo[3,2-e]indole

Ethyl pyruvate 1-acetyl-5-indolinylhydrazone was obtained by diazotization of 1-acetyl-5-aminoindoline with subsequent reduction of the diazonium salt and condensation of the hydrazine with ethyl pyruvate. A mixture of hydrogenated derivatives of linear and angular pyrroloindoles is formed as a result of cyclization of the hydrazone in polyphosphoric acid esters. Subsequent hydrolysis, decarboxylation, and dehydrogenation lead to 1H,5H-pyrrolo[2,3-f]indole and 3H,6H-pyrrolo-[3,2-e]indole.See [1] for Communication 5.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 504–507, April, 1982.     

The Asymmetric Transformation of a 1,2-Dihydro-3H-pyrrolo [1,2-a] Pyrrole-1-Carboxylate Ester

The second order asymmetric transformation of a 5-aroyl-1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylate ester to give a single enantiomer in high yield is described.     

Heterocyclic systems. II. Synthesis of 4H,6H-pyrrolo[1,2-a][4,1]benzoxazepine

The reduction of 1-(2-methoxycarbonylphenyl)pyrrole-2-carboxaldehyde by lithium aluminum hydride led to 1-(2-hydroxymethylphenyl)-2-hydroxymethylpyrrole, which was in turn transformed into 4H,6H-pyrrolo-[1,2-a][4,1]benzoxazepine through intramolecular dehydration. The reductive action of sodium borohydride, instead, allowed the preparation of 6-oxo-4H-pyrrolo[1,2-a][4,1]benzoxazepine.     

A convenient synthesis of 9H-dibenz[c,f]imidazo[1,2-a]azepin-9-ones

A convenient three step synthesis of 9H-dibenz[c,f]imidazo[1,2-a]azepin-9-ones from readily available 2-phenylimidazoline and a methyl benzoate is described.     

3-取代-(1H)-嘧啶[1,2-α]喹啉-1-酮和2-取代嘧啶[1,2a]苯骈咪唑-4-(10H)-酮的简便合成法

丙二酸亚异丙酯及乙烯基硫代缩酮均是重要的有机合成试剂。而新近开发的5-(双甲硫基亚甲基)丙二酸亚异丙酯(1)既具有丙二酸亚异丙酯的环状结构,又具有乙烯基硫代缩酮的结构特征,它是一种多功能新的合成试剂。其最重要的性质是它可与多种亲核试剂发生加成反     

Regiospecific synthesis of 3-substituted imidazo[1,2-a]pyridines,imidazo[1,2-a]pyrimidines,and imidazo[1,2-c]pyrimidine

3-Substituted imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, and imidazo[1,2-c]pyrimidine were obtained regiospecifically in yields of 35-92% in one pot by reaction of 2-aminopyridines or 2-(or 4-)aminopyrimidines, respectively, with 1,2-bis(benzotriazolyl)-1,2-(dialkylamino)ethanes.     

A convenient approach to the synthesis of 1-halomethyl-substituted 2,4,5,6-tetrahydro-1H-imidazo[1,2-a][1]benzazepines

Chemistry of Heterocyclic Compounds - Intramolecular halocyclization of N-allyl-4,5-dihydro-3H-1-benzazepin-2-amines, obtained by consecutive methylation and allylamination of benzazepin-2-ones, by...