Alkylation of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones

Reaction of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones with dimethyl sulfate and haloalkanes in DMF or DMSO in the presence of potassium hydroxide gives the 1-substituted 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones (N-substituted products) and 9,9a-dihydro-3H-imidazo[1,2-a]indoles (O-substituted products). The latter, on treatment with acids and bases, are converted into 1-alkoxycarbonylmethyl-2,3-dihydro-1H-indoles. 1-Ethoxycarbonyl-methyl-2,3-dihydro-1H-indoles on treatment with lithium aluminohydride undergoes cyclization to 2,3,9,9a-tetrahydrooxazolo[3,2-a]indole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 49–53, January, 1988.     

Study of reaction of 2,3,3-trimethyl-3H-indole with haloacetic acid amides. Synthesis of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones

In the reaction of 2,3,3-trimethyl-3H-indole with -chloro- and -iodoacetamides, 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolium salts are formed, which by the action of bases convert into imidazo[1,2-a]indol-2-one and 1-carbamoyl-2-methylene-2,3-dihydroindole. The latter compound can by cyclized into imidazo[1,2-a]indol-2-one by the action of acetic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 933–935, July, 1985.     

1,2,3,9a-Tetrahydro-9H-imidazo[1,2-a]indoles

When derivatives of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one or 1-carbamoylmethyl-2-methylene-2,3-dihydroindole are reacted with lithium aluminum hydride, derivatives of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indole are formed. Under the same conditions 1-(N-phenylcarbamoylmethyl)-2-methylene-2,3-dihydroindole is not cyclized to an imidazo[1,2-a]indole. WHen treated with proton acids imidazo[1,2-a]indoles are converted to 3H-indolium salts. Opening of the imidazolidine ring is also found when imidazo[1,2-a]indole is acylated with benzoyl chloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 227–230, February, 1987.     

Condensation of 1-Substituted 1,2,3,9a-Tetrahydro-9H-imidazo[1,2-a]indol-2-one Derivatives with Aromatic Aldehydes

Condensation of 1-alkyl-, 1-allyl-, and 1-benzyl-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones with benzaldehydes in acetic acid and subsequent treatment of the reaction mixture with potassium hydroxide afforded 1-substituted 9a-(2-phenylethenyl)-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one derivatives. 1-Methyl- and 1-ethyl-9a-[2-(4-dimethylaminophenyl)ethenyl]-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones were synthesized by alkylation of 9a-[2-(4-dimethylaminophenyl)ethenyl]-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one with methyl- and ethyl iodides in DMF in the presence of a strong base.     

Synthesis of 1H-imidazo[1,2-a]imidazole

The synthesis and structure analysis of the unknown 1H-imidazo[1,2-a]imidazole ( 1 ) is described. The preparation involves alkylation of 2-aminoimidazole with bromoacetaldehyde diethyl acetal and subsequent hydrolysis and cyclization with hydrochloric acid. The structure was characterized by mass spectrometry and by ¹H-, ¹⁵N- and ¹³C-nmr of 1 and by ¹H-nmr of its 1-benzyl derivative 8 . An independent synthesis of 8 was accomplished via cyclization of 2-(N-dichloroethyl-N-benzyl)aminoimidazole ( 11 ).     

Synthesis and ring transformations of 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-ones

Heating 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolinium chloride in the presence of hydrazine bishydrate produces regioselectively the five-membered heterocycle 1-amino-1,2,3,9a-tetrahydro-9,9,9a-trimethylimidazo[1,2-a]indol-2(9H)-one. The assignment of the structure is based on extensive ¹H, ¹³C and ¹⁵N NMR spectroscopic studies. No ring-chain tautomerism of the 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-one was observed to open-chain hydrazides or the corresponding six-membered 1,2,10,10a-tetrahydro[1,2,4]triazino[4,3-a]indol-3(4H)-one. Further transformations of 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-one were performed by treatment with aromatic aldehydes, acid chlorides and isocyanates giving access to 40 novel hydrazones, N,N′-diacylhydrazines, N-acyl-N′-carbamoylhydrazines and 1,3,4-oxadiazoles.     

Synthesis of 7-substituted imidazo[1,2-a]pyrimidin-5(1H)-ones

The synthesis of 7-substituted imidazo[1,2-a]pyrimidin-5(1H)-ones by either of 2 methods is reported.     

Synthesis of 3,9,9,9a-tetramethyl-1,2,3,9a-tetrahydro-9H-imidazo[1,2-<Emphasis Type="Italic">a</Emphasis>]-indol-2-ones by reaction of 2,3,3-trimethyl-3H-indole with 2-bromopropionamides

Alkylation of 2,3,3-trimethyl-3H-indole with 2-bromopropionamide and the subsequent treatment of the formed 1-(1-carbamoylethyl)-2,3,3-trimethyl-3H-indolium bromide with a base afforded 3,9,9,9a-tetramethyl-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one. Condensation of the 1-(1-carbamoylethyl)-2,3,3-trimethyl-3H-indolium salt with 2-hydroxy-1-naphthaldehyde gave a mixture of diastereomeric 1-(1-carbamoylethyl)spiro[2H-indole-2,3-[3H]naphtho[2,1-b]pyrans].Published in Khimiya Geterotsiklicheskikh Soedinenii, No 11, pp. 1690–1694, November, 2004.     

A Three-Component Synthesis of trifluoromethylated hexahydropyrrolo[1,2-a]imidazol-5-ones and hexahydropyrrolo[1,2-a]pyrimidin-6-ones

Chemistry of Heterocyclic Compounds - A three-component reaction of ethyl trifluoropyruvate, methyl ketones, and ethylenediamine or 1,3-diaminopropane afforded...     

Alkylation of 1,2,3,4,10,10a-hexahydropyrimido[1,2-a]indol-2-one

A mixture of N- and O-alkylation products is formed in the reaction of 1,2,3,4,10,-10a-hexahydropyrimido[1,2-a]indol-2-ones with ethyl iodide, allyl bromide, or benzyl chloride in DMFA (dimethylformamide) in the presence of potassium hydroxide. In the presence of aqueous solutions of acids with subsequent treatment with bases, the alkylation products are converted to 1-[2-(alkoxycarbonyl)-ethyl]-2-methylene-2,3-dehydro-1H-indoles. The reaction of 1,2,3,4,10,10a-hexahydropyrimido[1,2-a]indol-2-one with triethyloxonium fluoroborate gives 1-[2-(ethoxycarbonyl)ethyl]-2-methylene-2,3-dihydro-1H-indole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1224–1227, September, 1989.     

Synthesis of 5H-imidazo[2,1-c]pyrrolo[1,2-a][1,4]benzodiazepine

We have synthesized 5H-imidazo[2,1-c]pyrrolo[1,2-a][1,4]benzodiazepine 1 in five steps from 1-(2-amino-methylphenyl) pyrrole 4 . Amidino derivatives 11-12 have also been prepared.     

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.     

Synthesis of 1-and 7-substituted 2,3-dihydro-1h-pyrrolo[1,2-a]benzimidazoles

Cyclization of 5-substituted 2-(-chloroalkyl)benzimidazoles in the presence of sodium ethoxide gave some benzene-and pyrroldine-ring-substituted 2,3-dihydro-1H-pyrrolo[1,2-a]-benzimidazoles.Translated from Khimiya Geterotsklicheskikh Soedinenii, No.8, pp.1137–1139, August, 1974.     

Synthesis of 4-Aryl Benzimidazolo[1,2-a]-s-triazin-2-ones and 2-Aroylaminobenzimidazolo[1,2-b]-1,2,4-thiadiazolines

Reaction of 2-aminobenzimidazole with aroylisothiocyanates gave 2-aroylaminobenzimidazoles ( 3 ) and N-aroyl-N′-(benzimidazol-2-yl)-thioureas ( 4 ). The products obtained on reaction of 4 with PCl₅ in POCl₃, and with oxidising agents have been identified as 4-arylbenzimidazolo[1,2-a]-s-triazin-2-ones ( 5 ) and 2-aroylamino-benzimidazolo[1,2-b]-1,2,4-thiadiazolines ( 7 ) respectively.     

Synthesis of derivatives of pyrazino[1,2-a]pyrimidin-4-ones

3-Alkoxy-2-aminopyrazines have been condensed with ethyl ethoxymethylenemalonate and isopropylidene methoxymethylenemalonate to afford 9-alkoxypyrazino[1,2-a]pyrimidin-4-ones substituted in the first case by an ethoxycarbonyl group at 3 position.     

The mass spectra of some 1H-imidazo[1,2-a]pyrrolo[3,2-e]pyridines

We report here the mass spectral fragmentations of some derivatives of a new heterocyclic system 1H-imidazo[1,2-a]pyrrolo[3,2-e]pyridine. These compounds combine structural features of 1H-pyrrolo[2,3-b]pyridines and imidazo[1,2-a]pyridines, but follow fragmentation pathways similar to the former.     

Synthesis and nuclear magnetic resonance spectra of 2H-pyrido [1,2-a] pyrimidin-2-ones

Reaction of ethyl phenylpropiolate with several 2-aminopyridines afforded the corresponding 2H-pyrido[1,2-a] pyrimidin-2-ones in good yields. Analysis of the nmr spectra of these compounds and their hydrobromides were based on comparing their spectra with their 3-deuterated analogues. It was found that in these 2-oxo compounds, the proton at position-7 is shielded and absorbs together with the olefinie proton at position-3 in the region of 5 6.35-6.70 ppm. The latter proton could be used for differentiating these compounds from the corresponding 4-oxo isomers which have already been identified by the deshielded proton at pusition-6 near § 9.0 ppm. The ir and nmr spectral data for all these compounds are tabulated and discussed.     

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