Photocyclization reactions. Part 4 . Synthesis of naphtho[1,8-bc]-furans and cyclohepta[cd]benzofurans using photocyclization of Ethyl 2-(8-Oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetates and ethyl 2-(5-Oxo-6,7,8,9-tetrahydro-5H-benzocyclohepten-4-yloxy)acetates

Photocyclization reactions were carried out on ethyl 2-(8-oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetates 1a-e and ethyl 2-(5-oxo-6,7,8,9-tetrahydro-5H-benzocyclohepten-4-yloxy)acetates 2a-e in acetonitrile. Irradiation of 1a-e gave naphtho[1,8-bc]furanols 3a-e and naphtho[1,8-bc]furans 4a-e in 33–83% yields and ethyl acrylates 5b-d were produced in 3–25% yields during irradiation of 1b-d . On the other hand, 2a-e afforded cyclohepta[ad|benzofuranols 6a-e and cyclohepta[ad]benzofurans 7a-e in 44–87% yields. Ethyl acrylates 8b-d were also produced in 7–43% yields from irradiation of 2b-d . Substituent effects on photocyclization and reaction pathways are discussed.     

Pyrimido[4,5-f]quinazolines

The corresponding 6-dimethylaminomethylen-5-oxo-5,6,7,8-tetrahydroquinazolines were obtained from reactions of 2-substituted and 2,7-disubstituted 5-oxo-5,6,7,8-tetrahydroquinazolines with the dimethylacetal of DMF. Sixteen 2,8-disubstituted 5,6-dihydropyrimido[4,5-f]quinazolines were obtained from the reaction of 2-phenyl- and 6-(dimethylamino)methylen-5-oxo-2-(4-pyridyl)-5,6,7,8-tetrahydroquinazolines with guanidine and eight amidines. The corresponding 6-hydroxymethylene derivative was obtained by hydrolysis of 6-(dimethylamino)methylen-5-oxo-1-phenyl-5,6,7,8-tetrahydroquinazoline.     

2-Substituted 5-oxo-5,6,7,8-tetrahydroquinazolines

Twenty novel 2-substituted 5-oxo-5,6,7,8-tetrahydroquinazolines in reactions of 2-formyl-1,3-cyclohexanedione and its 5,5-dimethyl- and 5-phenyl derivatives with 4-chloro- and 4-carbonylaminobenzamidines, 3- and 4-carbamidinopyridines, 2-carbamidinopyrazine, 2-carbamidino-5-trifluoromethylpyridine, 1-carbamidinopyrrolidine, 4-carbamidinomorpholine, and 1-carbamidino-3,5-dimethylpyrazole have been obtained.Riga Technical University, Riga LV-1658, Latvia; e-mail: marina@osi.lv. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 212–26, February, 2000.     

Synthesis and reactions of 2-(4-pyridyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydroquinazoline

7,7-Dimethyl- and 7-phenyl-2-(4-pyridyl)-5-oxo-5,6,7,8-tetrahydroquinazolines were synthesized in the reactions of 2-formyl-5,5-dimethyl- and 5-phenyl-1,3-cyclohexanediones, respectively, with 4-amidinopyridine. The oxime, thiosemicarbazone, 4-quinazolyl-, nicotinoyl-, isonicotinoyl-, and 2-hydroxybenzoylhydrazones of 2-(4-pyridyl)-5-oxo-7,7-dimethyl-5,6,7,8-tetrahydroquinazoline were obtained. The reduction of this ketone by sodium borohydride leads to the 5-hydroxy derivative.     

Synthesis of 5,6,7,8-tetrahydro-5-oxopyrido[2,3-d]pyrimidine-6-carbonitriles and -6-carboxylic acid esters

Dieckmann ring closure reactions of 4-[(2-cyanoethyl)substituted amino]-2-phenyl-5-pyrimidinecarboxylates (Ha-f) afforded several 5,6,7,8-tetrahydro-5-oxo-2-phenylpyrido[2,3-d]pyrimidine-6- carbonitriles (IIIa-f). The open-chain intermediates (IIa-f) were prepared by dechloroamination of 5-carbethoxy-4-chloro-2-phenylpyrimidine (1a) with several 3-substituted amino- propionitriles. Alkylation of the sodium salt of 5,6,7,8-tetrahydro-8-methyl-5-oxo-2-phenyl-pyrido[2,3-d]pyrimidine-6- carbonitrile (IIIa) with methyl iodide in DMF resulted in methylation at C-6 to afford IV. Tosylation of IIIa in pyridine gave the corresponding tosyl ester (V) of the enolic form. Oxidative dehydrogenation at the 6,7-position resulted when IIIa reacted with thionyl chloride, affording 5,8-dihydro-8-methyl-5-oxo-2-phenylpyrido[2,3-d]pyrimidine-6- carbonitrile (VII). Dechloroamination of la or 5-carbethoxy-4-chloro-2-methylthiopyrimidine (Ib) with ethyl 3-ethylaminopropionate followed by Dieckmann cyclization of the resulting open-chain intermediates gave the corresponding ethyl 5,6,7,8-tetrahydro-5-oxopyrido[2,3-d]pyrimidine-6-carboxylates IX'a and IX'b, respectively. These exist predominately in the enol form and undergo alkylation and oxidation reactions similar to IIIa.     

Acetals of lactams and amides. 60. N- and O-alkylation of 5-oxo-5,6,7,8-tetrahydrocarbostyryils. Synthesis of isoxazolo[5,4-f]- and pyrazolo[3,4-f]quinolines

The alkylation of 5-oxo-5,6,7,8-tetrahydrocarbostyrils has been examined by GLC. It has been found that, irrespective of the reaction conditions and the alkylating agent used, both N- and O-alkylation occur. When triethyloxonium fluoroborate and N,N-DMF diethyl acetal are used O-alkylation predominates, and with alkyl halides, N-alkylation. Reaction of N-ethyl-5-oxo-5,6,7,8-tetrahydrocarbostyril and 2-ethoxy-5-oxo-5,6,7,8-tetrahydrotetrahydroquinoline with DMF diethyl acetal gives the 6-dimethylaminomethylene derivatives, treatment of which with hydrazine hydrate or hydroxylamine affording isoxazolo[5,4-f]- or pyrazolo[3,4-f]quinolines.For Communication 59, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 86–92, January, 1991.     

Reactions of 5,6,7,8-Tetrafluoro-4-hydroxy-2H-chromen-2-ones with methylamine

5,6,7,8-Tetrafluoro-4-hydroxy-2H-chromen-2-one reacts with methylamine to give methylammonium 5,6,7,8-tetrafluoro-2-oxo-2H-chromen-4-olate, regardless of the solvent. The reaction of 3-acetyl-5,6,7,8-tetrafluoro-4-hydroxy-2H-chromen-2-one with the same amine in ethanol or acetonitrile leads to the formation of methylammonium 3-acetyl-5,6,7,8-tetrafluoro-2-oxo-2H-chromen-4-olate, while in dimethyl sulfoxide 5,6,8-trifluoro-7-methylamino-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione is formed. The latter is also formed in the reaction of 5,6,7,8-tetrafluoro-4-hydroxy-3-(1-iminoethyl)-2H-chromen-2-one with methylamine in DMSO, whereas in ethanol and acetonitrile 5,6,7,8-tetrafluoro-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione is obtained. 5,6,7,8-Tetrafluoro-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione reacts with methylamine, yielding 7-mono-or 5,7-bis(methylamino)-substituted derivatives.     

Synthesis of Fluorine-Containing 2-(1-Aryl-4-oxo-1,4-dihydrocinnolin-3-yl)-2-oxoacetic Acids

Acid hydrolysis of ethyl 2-(1-aryl-5,6,7,8-tetrafluoro-4-oxo-1,4-dihydrocinnolin-3-yl)-2-oxoacetates gives 2-(1-aryl-5,6,7,8-tetrafluoro-4-oxo-1,4-dihydrocinnolin-3-yl)-2,2-dihydroxyacetic acids which undergo dehydration on heating in toluene to afford 2-(1-aryl-5,6,7,8-tetrafluoro-4-oxo-1,4-dihydrocinnolin-3-yl)-2-oxoacetic acids. Reactions of the latter with excess morpholine result in replacement of two fluorine atoms in positions 5 and 7 by the amine residues.     

Recent developments in the chemistry of perhydroindoles and perhydrocinnolines

Recent synthetic routes to the tetrahydro, hexahydro and octahydro derivatives of indoles are reviewed. An interesting one is the formation of 3-amino-4-oxo-4,5,6,7-tetrahydroindoles in the reaction of 2-phenacyl cyclohexane-l,3-diones with 1,1-disubstituted hydrazines. Antifertility, cns depressant and antiinflammatory activities have been encountered for perhydroindoles besides other biological activities. Hexahydrocinnolines are obtained from the reaction of 2-phenacyl (acetonyl) cyclohexanones and cyclohexane-1,3-diones with hydrazines, while octahydrocinnolines are formed from cyclohexanone-2-acetic acids and hydrazines in two steps. 5-oxo-5,6,7,8-hexahydrocinnolines and their oximes undergo anomalous and interesting aromatisation reactions. Some hexahydrocinnolines are cns depressants while octahydrocinnolines are analgesics. More importantly, they are precursors for interesting azamorphinans. Contribution No. 736 from Research centre     

Synthesis and pancreatic lipase inhibitory activities of some 1,2,4-triazol-5(3)-one derivatives

In this study, starting from 4-amino-5-(4-chlorobenzyl)-2,4-dihydro-3H-1,2,4-triazole-3-one ( 1 ), the 4-Amino-5-(4-chlorobenzyl)-2-undecyl-2,4-dihydro-3H-1,2,4-triazol-3-one ( 2 ) was first synthesized and this compound was converted to Schiff base derivatives ( 3a-e ). In the second step of the study, the 2-[3-(4-chlorobenzyl)-5-oxo-1-undecyl-1,5-dihydro-4H-1,2,4-triazole-4-yl]-acetohydrazide ( 6 ), which was used as a key product in the synthesis of many heterocyclic compounds was synthesized in four steps, and then this compound was converted into methylidene acetohydrazide ( 7a-e ), thiosemicarbazide ( 8a-e ), and 1,2,4-triazole-5-thione ( 9a-e ) derivatives. Also, in the last part of the study, 1,2,4-triazole-5-thione derivatives were changed into Mannich bases ( 10a-b ) bearing a 4-phenylpiperazine ring. These new compounds were tested with regard to pancreatic lipase (PL) inhibition activity, and compound 3b , 3d , 7d , 8d , and 9d showed a considerable anti-lipase activity at various concentrations. The activity of compounds 7b (IC₅₀ = 1.45 ± 0.12 μM) was the highest in terms of IC₅₀, comparable to that of orlistat, a well-known PL inhibitor used as an antiobesity drug.     

Methods for the synthesis of 5,6,7,8-tetrahydro-1,8-naphthyridine fragments for alphaVbeta3 integrin antagonists

The preparation of 3-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)propan-1-amine 2a and 3-[(7R)-7-methyl-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl]propan-1-amine 2b, key intermediates in the synthesis of alpha(V)beta(3) antagonists, is described. The syntheses rely on the efficient double Sonogashira reactions of 2,5-dibromopyridine 3 with acetylenic alcohols 4a/4b and protected propargylamines 10a-e followed by Chichibabin cyclizations of 3,3'-pyridine-2,5-diyldipropan-1-amines 9a/9b.     

Features of reactions of polyfluorinated ethyl 4-oxo-2-pnenyl-4H-chromene-3-carboxylates with N-nucleophiles

Ethyl 5,6,7,8-tetrafluoro-4-oxo-2-phenyl-4H-chromene-3-carboxylate in reactions with primary amines is characterized by a chromone-coumarin rearrangement affording 3-[amino(phenyl)methylene]-6,7,8-trifluoro-2H-chromene-2,4(3H)-diones, and ethyl 4-oxo-2-phenyl-5,6,7,8-tetrafluoro-4H-chromene-3-carboxylate characteristically adds the amine at the C² site of the flavone furnishing 3-amino-3-phenyl-2-(2,3,4,5-tetrafluoro-6-hydroxybenzoyl)acrylates which depending on the substituent at the amino group are capable of intramolecular cyclization into 3-[(alkylamino)(phenyl)methylene]-5,6,7,8-tetrafluoro-2H-chromene-2,4(3H)-dione or in the case of benzylamine substituent, into ethyl 1-benzyl-5-hydroxy-4-oxo-2-phenyl-6,7,8-trifluoro-1,4-dihydroquinoline-3-carboxylate. The main process in the reaction of tri- and tetrafluoroflavones with secondary amine (1-methylpiperazine) is the nucleophilic substitution at the C⁷ of flavone. In the reaction with 1,2-phenylenediamine 3-[(2-aminophenyl)amino]-3-phenyl-2-(2,3,4,5-tetrafluoro-6-hydroxybenzoyl)acrylate was obtained from tetrafluoroflavone and 1H-benzimidazol-2-yl(3,4,5-trifluoro-2-hydroxyphenyl)methanone, from trifluoroflavone.     

4,5-Dihydropyrazolo[3,4-f]quinazolines

By reaction of 6-dimethylamino-5-oxo-2-phenyl-5,6,7,8-tetrahydroquinazoline with hydrazine, phenylhydrazine, 4-bromo-, 4-chlorophenylhydrazines, and also reaction of 6-dimethylaminomethylene-5-oxo-2-(4-pyridyl)-5,6,7,8-tetrahydroquinazoline with hydrazine, 4-methoxy- and 2-carboxyphenylhydrazines, we have obtained the corresponding 7-phenyl(4-pyridyl)-substituted 1H(2H)- or 1-aryl-4,5-dihydropyrazolo[3,4-f]quinazolines. Methylation of 7-phenyl-4,5-dihydro-1(2H)-pyrazolo[3,4-f]quinazoline by methyl iodide led to its 2-methyl derivative.     

N-monosubstituted 6-Aminomethylene-5-oxo-2-phenyl-5,6,7,8-tetrahydroquinazolines

We have obtained the corresponding N-monosubstituted 6-aminomethylene-5-oxo-2-phenyl-5,6,7,8-tetrahydroquinazolines by transamination of 6-dimethylaminomethylene-5-oxo-2-phenyl-5,6,7,8-tetrahydroquinazoline with histamine, tryptamine, 3-(1-imidazolyl)- and 3-(4-morpholyl)-propylamines, 4-amino-1-benzylpiperidine, 2-(1-naphthylamino)ethylamine, 2-pyridylmethylamine, 4-chlorobenzylamine, ethanolamine, 1-aminoadamantane, remantadine, 2-aminodimedone, aniline, 3-trifluoromethylaniline, 4-aminoantipyrine, 2-aminobenzimidazole, 2-amino-5-methylbenzothiazole, 7-amino-4-methylcoumarin, 1-amino-4-methylpiperazine, 2-(2-aminophenyl)benzimidazole, 3-(4-aminophenylamino)-2-cyano-5,5-dimethylcyclohex-2-en-1-one, and 3-amino-2-(2-hydroxyethyl)-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazole. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1230–1235, August, 2005.     

3,6,6-trimethyl-4-oxo-1-(2-pyridyl)-4,5,6,7-tetrahydroindazole in Schmidt reaction and Beckmann rearrangement conditions for the 4-hydroxyimino derivative

Treatment of 3,6,6-trimethyl-4-oxo-1-(2-pyridyl)-4,5,6,7-tetrahydroindazole with sodium azide in acids gives 3,7,7-trimethyl-5-oxo-1-(2-pyridyl)-5,6,7,8-tetrahydro(4H)pyrazolo[4,3-b]azepine. Heating 1-(2-pyridyl)-3,6,6-trimethyl- and 1-phenyl-6,6-dimethyl-4-hydroxyimino-4,5,6,7-tetrahydroindazoles in polyphosphoric acid gives 1-phenyl-5,6-dimethyl- and 1-(2-pyridyl)-3,5,6-trimethyl-4-aminoindazole respectively: The reactions of the latter with 4-dimethylaminobenzaldehyde gave the 4-(4-dimethylaminobenzalamino) derivative and with 2-formyldimedone the 4-(4,4-dimethyl-2,6-dioxocyclohexylidenemethylamino) derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 830–834, June, 2000.     

5,6,7,8-Tetrafluoro-4-hydroxycoumarin derivatives in reactions with o-phenylenediamine

The reactions of 5,6,7,8-tetrafluoro-4-hydroxycoumarin derivatives with o-phenylenediamine occur with pyrone heterocycle cleavage and formation of substituted benzodiazepin-2-ones. 5,6,7,8-Tetrafluoro-4-hydroxycoumarin affords 4-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)-2,3-dihydro-1H-1,5-benzodiazepin-2-one, 3-acetimidoyl-5,6,7,8-tetrafluoro-4-hydroxycoumarin produces 3-(3,4,5,6-tetrafluoro-2-hydroxybenzoyl)-4-methyl-1,2-dihydro-1H-1,5-benzodiazepin-2-one, and 3-acetyl-5,6,7,8-tetrafluoro-4-hydroxycoumarin yields both these heterocycles.     

Synthesis of some 5,6,7,8-tetrahydro-4-cinnolone derivatives and 1-methyl-3-arylacetyl-4,5,6,7-tetrahydroindazoles

2-Arylidene-3-oxo-2,3,4,5,6,7-hexahydrobenzo[b]furans 2 react with hydrazine hydrate to afford 5,6,7,8-tetrahydro-4-cinnolones. By methylation, these compounds gave the corresponding N-1 and N-2 methyl derivatives. The mesoionic compounds are obtained, accompanied by 3-arylacetyl-4,5,6,7-tetrahydroindazoles upon reaction of 2 with methylhydrazine.     

One-Pot Synthesis of Tetrahydrobenzo-[b]-pyran Derivatives in Aqueous Media

In modem organic chemical research, 4H-benzo-[b]-pyran and their derivatives have attracted strong interest due to their useful biological and pharmacological properties. Herein, we report a clean one-pot synthesis of 2-amino-3-cyano-4-aryl-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydro-benzo-[b]-pyrans from aromatic aldehyde, malononitrile and 5,5-dimethyl-1,3-cyclohexadione using hexadecyl trimethyl ammonium bromide (HTMAB) as the catalyst. This method provides several advantages such as high yield, simple work-up procedure and environmental friendliness. All the products were characterized by 1H NMR and IR analyses.     

Studies on the esterifications of 9-（hydroxyimino）-4-methyl-8,9-dihydrofuro[2,3-h]chromen-2-one with acid chlorides under different conditions

The esterifications of 9-（hydroxyimino）-4-methyl-8,9-dihydrofuro[2,3-h]chromen-2-one （4） with acid chlorides afforded normal oxime-esters 3a-e in 35-78% yields in presence of excessive 4-dimethylaminopyridine as the acid scavenger, whereas the reactions gave unexpected 8-substituted products N-（8-chloro-4-methyl-2-oxo-2H-furo-[2,3-h]chromen-9-yl）amides （5a-c） and 4-methyl-2,9-dioxo-8,9-dihydro-2H-furo[2,3-h]chromen-8-ylcarboxyloates （6d-e） by using excessive acid chlorides. The structures of 10 new compounds were determined by 1H NMR, 13C NMR, MS and HRMS, and the possible mechanism for the formation of unexpected products 5a--c and 6d-e was also proposed.     

Organocatalyzed enantioselective synthesis of 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carboxylates

The organocatalyzed enantioselective synthesis of biologically active 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carboxylate derivatives was achieved using bifunctional cinchona alkaloids as the catalysts. Using quinine thiourea as the catalyst, the tandem Michael addition-cyclization reaction between 1,3-cyclohexanediones and alkylidenecyanoacetate derivatives gives the desired products in high yields (up to 92%) and good ee values (up to 82%).