Interaction of 4,5,7-Trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-<Emphasis Type="Italic">c</Emphasis>]pyridines with Acetic and Trifluoroacetic Anhydrides

The reactions of NH- and N-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo-[3,2-c]pyridines and their 2-substituted derivatives with acetic and trifluoroacetic anhydrides have been studied. Trifluoroacetylation of tetrahydropyrrolo-[3,2-c]pyridines occurs at the α-position of the pyrrole ring, whereas cleavage of the tetrahydropyridine ring with formation of 3-vinylpyrroles occurs with acetic anhydride. 2-Acetyl-4,5,7-trimethyl-1-vinyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine was synthesized by the Vilsmeier-Haack reaction.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, 751–760. May, 2005.     

Synthesis of pyrylium and pyridine derivatives of benzofuran

Acylation of benzo[b]-2-furyl acetone was used to synthesize 2,9-disubstituted benzofuro[3,2c] pyrylium perchlorates, which were converted in high yields to the corresponding benzofuro-[3,2-c]pyridines. The molecular diagram of the pyrylium cation is examined. The IR, UV, and NMR spectra of the synthesized compounds are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 450–456, April, 1973.     

Synthesis and nitration of NH- and N-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines

It has been shown that the most efficient catalysts for the synthesis of 4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine from 1,2,5-trimethylpyridin-4-one and acetylene under Trofimov conditions are rubidium and potassium hydroxides. Use of Triton B or a mixture of trimethylbenzylammonium chloride with rubidium hydroxide as catalyst gives O-alkylated oxime. Their configurations and conformations were established through separation of the individual isomers of 1-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines. Acetyl nitrate nitration of the cis isomer of this compound gave the 2- and 3-nitro derivatives. Similar nitration of 4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine gave the 2-nitro-7-hydroxy derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1375–1380, October, 1991.     

Nouvelles voies d'accès à des aryl-4 thiéno[2,3-c]pyridines et à des aryl-7 thiéno[3,2-c]pyridines

4-Arylthieno[2,3-c]pyridines and 7-arylthieno[3,2-c]pyridines have been prepared by heating in polyphosphoric acid 2-(2-thenylamino>l-arylethanols or propanols and 2- 3-thenylamino>l-arylethanols or propanols, respectively.) Under the Beckmann rearrangement conditions, oximes of 4-aryl-4,5-dihydro-6H-cyclopenta[b]thiophen-6-one lead to 4-aryl-4,5- dihydro-6H-thieno[2,3-c]pyridin-7-one.     

Synthesis of 3-amino derivatives of benzo[b]furo[2,3-c]pyridines

The reaction of 1,7-dimethyl-3(2H)-benzo[b]furo[2,3-c]pyridone with phosphoric acid amides gave 1,7-dimethyl-3-dimethylamino (morpholino)benzo[b]furo[2,3-c]pyridines. A method for the synthesis of 3-amino derivatives of 4-nitrobenzo[b]furo[2,3-c]pyridines, which consists in heating 1,7-dimethyl-4-nitro-3(2H)-benzo[b]furo[2,3-c]pyridone with hexamethyldisilazane and secondary or primary amines in pyridine, was developed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1552–1555, November, 1991.     

Synthesis of 2-R-4,5,7-trimethyl-1-vinyl-4,5,6,7-tetrahydropyrrolo[3,2-<Emphasis Type="Italic">c</Emphasis>]pyridines

The synthesis of 1-vinyltetrahydropyrrolo[3,2-c]pyridines substituted at C₍₂₎ has been accomplished, based on 4,5,7-trimethyl-1-vinyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine and its 2-formyl-substituted derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1709–1716, November, 2004.     

One-pot synthesis of 3-(sulfonyl)-5,6,7,8-tetrahydro-4H-pyrano[3,2-c]pyridines through a cascade Michael/cyclization reaction

In this paper, a straightforward and valid three-component Michael/cyclization reaction of (E)-1-methyl-3-(arylidene)piperidin-4-ones, 2-(sulfonyl)acetonitriles, and aromatic aldehydes was explored for the preparation of potentially biologically active 3-(sulfonyl)-5,6,7,8-tetrahydro-4H-pyrano[3,2-c]pyridines under mild reaction conditions. More diverse 3-(sulfonyl)-5,6,7,8-tetrahydro-4H-pyrano[3,2-c]pyridine derivatives were constructed in satisfactory yields (up to 97%). The chemical structure of newly synthesized 3-(sulfonyl)-5,6,7,8-tetrahydro-4H-pyrano[3,2-c]pyridines were identified with ¹H-NMR, ¹³C-NMR, and mass spectrometry analysis. The recommendable method features a simple and direct workup, easy access to initial materials, high atom utilization efficiency, high final product yields, and a wide range of substrate adaptability.     

Lactams of acetals and acid amides, 45. Synthesis of condensed 2-pyridones from activated amides,lactams, and lactones

By reaction of lactim ethers with N-substituted cyanoacetamides, the corresponding enaminoamides were obtained, cyclization of which by dimethylformamide acetal gave derivatives of pyrrolo[3,2-c]pyridine, 1,6-naphthyridine, and pyrido[4,3-b]azepine, having a substituent at the nitrogen atom of the pyridone ring. N-substituted furo[3,2-c]pyridines were synthesized from the diethyl acetals of butyrolactone and 3-(dimethylaminomethylene)butyrolactone and dimethylformamide acetal.For communication 44, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 929–932, July, 1985.     

Condensed O-, N-heterocycles by the transformation of azidoacrylates

Summary A number of furo[3,2-c]pyridines (4a–4d) and benzo[b]derivative (4e), as well as pyrrolo[2,3-4,5]furo[3,2-c]pyridine (8) were prepared by reaction of the corresponding iminophosphoranes, available from ethyl azidoheteroacrylates and triphenylphosphine, with phenyl isocyanate. The appropriate azidoheteroacrylates were used for the preparation of some substituted furo[3,2-b:4,5-b]dipyrroles (6). The reactions of the prepared compounds are described.

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Kondensierte O-, N-Heterocyclen durch Umwandlung von Azidoacrylaten

Zusammenfassung Eine Anzahl von Furo[3,2-c]pyridinen (4a –4d), ein Benzo[b]derivat (4e) und Pyrrolo[2,3:4,5]furo[3,2-c]pyridin (8) wurden durch die Reaktion von Phenylisocyanaten mit den entsprechenden Iminophosphoranen dargestellt, die aus Ethyl-azidoheteroacrylaten und Triphenylphosphin leicht zugänglich sind. Die entsprechenden Azidoacrylate wurden zur Synthese einiger Furo[3,2-b:4,5-b]dipyrrole (6) verwendet. Die Reaktionen einiger dieser Verbindungen werden beschrieben.

     

Synthesis and pharmacological evaluation of 5-[2′-(1H-tetrazol-5-yl)-biphenyl-4-ylmethyl]-4,5,6,7-tetrahydro-thieno[3,2-c]pyridine derivatives as platelet aggregation inhibitors

One pot synthesis and characterization of new 5-[2′-(1H-tetrazol-5-yl)-biphenyl-4-ylmethyl]-4,5,6,7-tetrahydro-thieno[3,2-c]pyridines (3a–k) using amides (2a–k) were reported. The prepared 5-[2′-(1H-tetrazol-5-yl)-biphenyl-4-ylmethyl]-4,5,6,7-tetrahydro-thieno[3,2-c]pyridine (3a) is a bioisostere of 4′-(6,7-dihydro-4H-thieno [3,2-c]pyridin-5-ylmethyl)-biphenyl-2-carboxylic acid (1), having good in vivo antithrombotic activity compared with Clopidogrel. The new tetrazole derivatives (3a–k) were screened for their in vitro activity as platelet aggregation inhibitors.     

Synthesis of N-substituted 1H-indeno[2,1-b]pyridines

It was established that N-phenacyl and p-nitrophenacyl bromides and N-methyl-1-azafluorenium iodide, as well as N-phenacyl-7-nitro-1-azafluorenium bromide, are converted to N-substituted 1H-indeno[2,1-b]pyridines rather than to the corresponding yilds or indenoindolizines upon treatment with bases under various conditions. All of the pseudoazulenes of this type were isolated in the form of crystalline black or dark-violet substances. In contrast to pseudoazulenes of the 1H-indeno[1,2-b]-and 2H-indeno[2,1-c]pyridine series, they are stable both in the solid state and in solutions. 1H-1-Methylindeno[2,1-b]pyridine forms a perchlorate and a picrate (retention of the pseudoazulene structure) but is converted to N-methyl-1-azafluorenium chloride by the action of hydrogen chloride. Spectral characteristics are presented for all of the compounds obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1511–1515, November, 1980.     

Steroido[3,2-b](carbazole-1-oxonium) salts

The reaction of 2-hydroxymethylene-3-ketosteroids with 2-ketoindoline in the presence of hydrogen chloride gives steroido[3,2-b](carbazole-1-oxonium) chlorides, which split out a 2-ketoindoline molecule under the influence of phenylhydrazine and are converted to steroido[3,2-c]-1-phenylpyrazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 219–221, February, 1973.     

Furopyridines. XX. Wittig-horner reaction of a phosphonate of reissert analogues of furo[3,2-c]-, -[2,3-c]- and -[3,2-b]pyridines

Furo[3,2-c]-( 1a ), -[2,3-c]- ( 1b ) and -[3,2-b]pyridine ( 1c ) were reacted with isopropyl chloroformate and trimethyl phosphite to give dimethyl 5-isopropoxycarbonyl-4,5-dihydrofuro[3,2-c]pyridine-4-phosphonate ( 2a ), dimethyl 6-isopropoxycarbonyl-6,7-dihydrofuro[2,3-c]pyridine-7-phosphonate ( 2b ) and dimethyl 4-isopropoxycarbonyl-4,7-dihydrofuro[3,2-b]pyridine-7-phosphonate ( 2c ) as unstable syrups. Reaction of 2b and 2c with n-butyllithium and then with benzaldehyde, p-methoxybenzaldehyde, p-cyanobenzalde-hyde or propionaldehyde afforded the normal Wittig reaction products 5b-H, 5b-OMe, 5b-CN, 5b-Et, 5c-H, 5c-H, 5c-OMe and 5c-CN , except for 2b with propionaldehyde. While, the same reactions of compound 2a and the reaction of 2b with propionaldehyde afforded the unexpected products, 5-isopropoxycar-bonylfuro[3,2-c]pyridinio-4-aryl-(or ethyl)methoxides 3a-H, 3a-OMe, 3a-CN and 3a-Et , 4-(1′-aryl(or ethyl)-1′-hydroxymethyl)furo[3,2-c]pyridines 4a-H, 4a-OMe, 4a-CN and 4a-Et accompanying formation of the normal products. Treatment of the normal Wittig reaction products with lithium diisopropylamide and then with acetone gave the derivatives alkylated at the 2-or the benzylic positions.     

2-Dichloromethyl-4-methyl-2,3-dihydrofuro[3,2-c]-quinoline derivatives

Substituted 2-dichloromethyl-4-methyl-2,3-dihydrofuro[3,2-c]quinolines were obtained by cyclization of substituted 2-methyl-3-(3,3-dichloroallyl)-4-hydroxquinolines, and 2-dichloromethyl-2,4-dimethyl-2,3-dihydrofuro[3,2-c]quinolines were isolated from 2-methyl-3-(2-methyl-3,3,dichloroallyl)-4-hydroxyquinolines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 84–86, January, 1973.     

Synthesis,structure, and tautomerism of 3a,7-dimethyl-4,6-diphenyl-2-ethynyl-7a-hydroxyperhydropyrrolo[3,2-c]pyridine

Isomeric [with respect to the fusion of the piperidine and pyrrolidine rings, as well as with respect to the mutual orientation of the substituents attached to the C₍₂₎ and C_(3a) carbon atoms] 3a, 7-dimethyl-4,6-diphenyl2-ethynyl-7a-hydroxyperhydropyrrolo[3,2-c]pyridines were isolated for the first time in the reaction of 3,5-dimethyl-2,6-diphenyl-4-piperidinone oxime with acetylene under the conditions of the Trofimov reaction under pressure. It was established that, in solutions, the isomers of this compound with an axial-equatorial fusion of the rings exist in the form of ring—chain tautomers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 903–914, July, 1992.     

A new synthesis of benzofuro[3,2-c]pyridines

The condensation of O-phenylhydroxylamine with piperidin-4-one and 3-methylpiperidin-4-one has given 1,2,3,4-tetrahydrobenzofuro[3,2-c]pyridine and 4-methyl-1,2,3,4-tetrahydro-benzofuro [3,2-c]pyridine, and these have been dehydrogenated to the corresponding heteroaromatic system of benzofuro[3,2-c]pyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.7, pp. 908–909, July, 1973.     

Synthesis of pyrido[1,2-c][1,3]benzoxazines based on 1-benzyl-3-hydroxy-3-methyl-6-(2-benzyloxyphenyl)-4-piperidones

The stereomeric 1-benzyl-3-hydroxy-3-methyl-6e-(2-bemyloxyphenyl)-4-piperidones on debenzylation and subsequent reaction with formaldehyde are converted into cis- and trans-1,3,4-10b-tetrahydro-3-hydroxy-3-methyl-2-oxopyrido-[1,2-c][1,3]benzoxazines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 124–127, January, 1991.     

Electrophilic cyclization of o-acetoxy- and o-benzyloxyalkynylpyridines: an easy entry into 2,3-disubstituted furopyridines

[reaction: see text] 2,3-Disubstituted furo[3,2-b]pyridines, 2,3-disubstituted furo[2,3-b]pyridines, and 2,3-disubstituted furo[2,3-c]pyridines are readily prepared under mild conditions via the palladium-catalyzed cross-coupling of 1-alkynes with o-iodoacetoxy- or o-iodobenzyloxypyridines, followed by electrophilic cyclization by I(2) or by PdCl(2) under a balloon of carbon monoxide.     

Synthesis of dimethylamino derivatives of some condensed heterocycles from dimethylphosgeneimmonium chloride

Diazo coupling of indazole-3-diazonium chloride with 1-(2,4-dinitrophenyl)-3,5-bis(dimethylamino)pyrazole, obtained from dimethylphosgeneimmonium chloride, and subsequent cyclization of the azo compound lead to the formation of the dimethylamino derivatives of a new polycyclic system — benzo[h]dipyrazolo[3,2-c:3,4-e]-1,2,4-triazine. Previously unknown 3-dimethylamino derivatives of 1,2,4-triazolo-[3,4-b]benzothiazole were synthesized by reaction of dimethylphosgeneimmonium chloride with 2-hydrazinobenzothiazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 403–406, March, 1978.     

The annelation of the 2-aminopyran-4-one ring to condensed thiophenes

The reaction of arylacetonitriles with the methyl ester of 3-hydroxybenzo[b]thiophene-2-carboxylic acid in the presence of a basic catalyst leads to the previously unreported 2-amino-3-arylbenzo[4,5]thieno[3,2-b]pyran-4-ones. Under the same conditions, the ethyl ester of 4,6-dimethyl-3-hydroxythieno[3,2-c]pyridine-2-carboxylic acid reacts to form derivatives of a new heterocyclic system, pyrano[2,3-4,5]-thieno[3,2-c]pyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1476–1478, November, 1983.