Synthesis of 1-iodo-1,2,3,4,4a,9a-hexahydrocarbazoles and their isomerization into 3-iodo-2,4-propano-1,2,3,4-tetrahydroquinolines

The reactions of 2-(cyclohex-2-enyl)-4,5-difluoroaniline or N-methyl-2-(cyclohex-2-enyl)aniline with I₂ in CCl₄ in the presence of NaHCO₃ give 1-iodo-1,2,3,4,4a,9a-hexahydrocarbazoles, which isomerize in MeCN into the corresponding 3-iodo-2,4-propano-1,2,3,4-tetrahydroquinolines in quantitative yields.     

An efficient synthetic route to chiral 4-alkyl-1,2,3,4-tetrahydroquinolines: enantioselective synthesis of (R)-4-ethyl-1,2,3,4-tetrahydroquinoline

An efficient synthetic route to non-racemic chiral 4-alkyl-1,2,3,4-tetrahydroquinoline is described. (4R)-4-Ethyl-1,2,3,4-tetrahydroquinoline was obtained by the organoaluminum promoted modified Beckmann rearrangement involving the oxime sulfonate of (3R)-3-ethylindan-1-one. The required optically active indanone was obtained via an asymmetric conjugate reduction of (E)-ethyl 3-phenylpent-2-enoate.     

Synthesis of 1,2,3,4-tetrahydroquinolines and 1,2,3,4-tetrahydro- 1,6-naphthyridines by a directed lithiation reaction

N-(tert-butoxycarbonyl)anilines (7), are easily converted in a one pot reaction sequence into the N- (tert-butoxycarbonyl)-1,2,3,4-tetrahydroquinolines (8), by directed ortho lithiation followed by reaction with 1- chloro-3-iodopropane, hence providing a new versatile quinoline ring nucleus synthesis. In an analogous reaction 2-N-(tert-butoxycarbonyl)- and an 2-N-(pivaloylamino) pyridine are converted to 1,2,3,4-tetrahydro-1,6- naphthyridines.     

Synthesis of 3-aryl-substituted 2-benzopyrylium salts with a free α position

A method for the synthesis of the previously unknown 3-aryl-substituted 6,7-dimethoxy-2-benzopyrylium salts with a free position by the formylation of 3,4-dimethoxydeoxybenzoins with butyl dichloromethyl ether in the presence of anhydrous AlCl₃ has been developed. The pyrylium salts, which were isolated in high yield in the form of stable perchlorates, readily exchange their heteroatom for nitrogen under the action of aqueous ammonia.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 7, pp. 1013–1014, August, 1970.     

Synthesis of 2-alkyl-6-phenyl-3, 4-c cycloheptenopyrylium salts

A method is given for synthesizing 2-alkyl-6-phenyl-3, 4-cycloheptenopyrylium perchlorates, obtained in 45–55% yields by acylating cycloheptenylacetophenone with anhydrides of aliphatic acids in the presence of 70% perchloric acid. Treatment of the pyrylium salts with ammonia gives a good yield of 2-alkyl-6-phenyl -3, 4-cycloheptenopyridine.     

Synthesis of 2-alkyl(aryl,hetaryl)-4-methyl-1,2,3,4-tetrahydroquinolines

We have developed a preparative, three stage of synthesis of substituted 1,2,3,4-tetrahydroquinolines. Treatment of N-aryl-imines with allylmagnesium bormide gave N-aryl-N-alkenylamines which were cyclized to the tetrahydroquinolines. The configurations and conformations of the 4-methyl-1,2,3,4-tetra-hydroquinolines containing different 2- substituents have been determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 73–78, January, 1994.     

Non-steroidal antiinflammatory agents. 3. Synthesis of 3-hydroxy-3-hydroxyphenyl-2,4-dioxo-1,2,3,4-tetrahydroquinolines

The acid-catalyzed condensation of quinisatines 5a-c or their aminals 4a-c with phenols 6a-i led to a number of 3-hydroxy-3-hydroxyphenyl-2,4-dioxo-1,2,3,4-tetrahydroquinolines 7a-s which were considered as potential antiinflammatory agents.     

Acid-catalyzed acylation of 4-alkyl-3-azapyrylium salts and the synthesis of 4-acylaminopyrylium salts

4-Alkyl-3-azapyrylium salts undergo acylation at the alkyl group under acid-catalyzed conditions to give 4-acylmethyl-3-azapyrylium derivatives, which upon heating in proton-donating solvents recyclize to give 4-acylaminopyrylium salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 265–269, February, 1991.     

Synthesis of 3-alkyl-4-aminofurazans

A “one-pot” method for the synthesis of 3-alkyl-4-aminofurazans from ethyl β-alkyl-β-oxopropionates was developed. The multistep process involves hydrolysis of the ester, nitrosation at the activated methylene group, and treatment of the resulting intermediate with an alkaline solution of hydroxylamine in the presence of urea. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1007–1012, April, 2005.     

Synthesis of enantiomers of 6-nitro- and 6-amino-2-methyl-1,2,3,4-tetrahydroquinolines

Enantiomers of 2-methyl-6-nitro-1,2,3,4-tetrahydroquinoline have been obtained by kinetic resolution of racemic 2-methyl-1,2,3,4-tetrahydroquinoline in acylation with acyl chlorides of N-protected amino acids followed by regioselective nitration of the diastereoisomeric amides and acidic hydrolysis. The introduction of a trifluoroacetyl protecting group into the position 1 of the enantio pure nitro compound followed by the reduction led to (S)-6-amino-2-methyl-1-trifluoroacetyl-1,2,3,4-tetra-hydroquinoline in a high yield.     

Synthesis and hydroxylation of 1-alkyl- and 7-alkyl- 1,3,7-triazapyrenium salts

The regioselectivity of quaternization of 1,3,5-triazapyrenes by alkyl halides has been studied. Oxidative hydroxylation of 1-alkyl- and 7-alkyl-1,3,7-triazapyrenium salts gives 1-alkyl-1,2-dihydro-1,3,7-triazapyren-2-ones or 7-alkyl-6,7-dihydro-1,3,7-triazapyren-6-ones respectively. In the absence of an oxidant the hydroxylation of the 1-alkyl-1,3,7-triazapyrenium salts leads to a hydrolytic cleavage of the heterocycle.     

Use of quinolinium salts in parallel synthesis for the preparation of 4-amino-2-alkyl-1,2,3,4-tetrahydroquinoline

Compounds of pharmacological interest containing a 4-amino-2-alkyl-1,2,3,4-tetrahydroquinoline core structure were prepared starting from 4-chloroquinoline. This has been executed both in solution with a 1-benzyl-4-chloroquinolinium salt and on a solid support with a 1-(4-benzyloxybenzyl-PS)-4-chloroquinolinium resin as key intermediates. Diversification of such intermediates was accomplished through N-arylation of position 4 and subsequent nucleophilic addition of Grignard reagents of position 2 to deliver the expected 4-amino-2-alkyl-1,2,3,4-tetrahydroquinolines in 20-60% yields. The methods described within clearly demonstrate that the quinolinium salts are very efficient intermediates for parallel synthesis.     

Recyclization of 3-alkyl- and 1,3-dialkylisoquinolinium salts to naphthylamines

3-Methyl- and 3-benzylisoquinolinium salts undergo rearrangement to 2-alkylaminonaphthalenes under the influence of alcohol solutions of alkylamines. The rearrangement of 1,3-dimethyl- and l-methyl-3-benzylisoquinolinium salts leads to both 1- and 2-alkylaminonaphthalenes with predominance of the former.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1272–1277, September, 1980.     

Synthesis of 4-alkyl-3-pyridinols from 3-benzyloxypyridine

The addition of Grignard reagents to the 1-phenoxycarbonyl salt of 3-benzyloxypyridine and a catalytic amount of cuprous iodide afforded 4-alkyl-3-benzyloxy-1-phenoxycarbonyl-1,4-dihydropyridines in good yield. The crude dihydropyridines were aromatized with o-chloranil to give 4-alkyl-3-benzyloxypyridines, which were debenzylated with hydrogen and 10% palladium on carbon to provide 4-alkyl-3-pyridinols.     

Synthesis and structure of 2-aryl-2,4-dimethyl-1,2,3,4-tetrahydroquinolines and 1,3-disubstituted indenes

It has been shown that the intramolecular cyclization of N-(1-arylbutenyl)arylamines under acid catalysis conditions may proceed in two directions with the formation of 2-aryl-2,4-dimethyl-1,2,3,4-tetrahydroquinolines and 1,3 disubstituted indenes.     

Synthesis and synthetic utility of 1-acyl-2-alkyl-4-trimethylstannyl-1,2-dihydropyridines

1-Acyl-2-alkyl-1,2-dihydropyridines were prepared from 4-trimethylstannylpyridine and Grignard reagents. This methodology was utilized in the synthesis of N-methyl-2-azatricyclo[5.3.1.0]undecane.     

Synthesis and configuration of 4-alkyl-2-methyl-3,4-diphenyl-1,2-thiazetidine 1,1-dioxide

4-Alkyl-2-methyl-3,4-diphenyl-1,2-thiazetidine 1,1-dioxide 5, 6 and 7 were obtained from 2-methyl-3,4-diphenyl-1,2-thiazetidine 1,1-dioxide 1 by reaction of its anion 4 with alkyl halides. cis- and trans-Configuration of the 4-alkylated products were determined by ¹H-nmr and NOE difference spectro-scopy studies.     

Condensation of 2-alkyl-4-oxo-1,3-benzoxazinium salts with carbonyl compounds and their heteroanalogs

A method is proposed for the synthesis of 2-(-dimethylaminovinyl)-4-oxo-1,3-benzoxazinium salts and dimethyl (4-oxo-3H-1,3-benzoxazine-2-methylene) sulfonium salts by condensation of 2-alkylbenzoxazinonium salts with dimethylformamide and dimethyl sulfoxide.Translated from Khimiya Geterotsiklichesikikh Soedinenii, No. 3, pp. 328–331, March, 1977.     

Synthesis of 1-alkyl-1,2,4-triazolium 4-nitroimides by alkylation of 4-nitramino-1,2,4-triazole salts

A method for the synthesis of 1-alkyl-1,2,4-triazolium 4-nitroimides was developed based on alkylation of 4-nitramino-1,2,4-triazole Na and Ag salts with halo- and dihaloalkanes.