Spiro[(2,3-dihydro-2-oxo-imidazo[1,2-a]pyridine)-3,3-(3,4-dihydro-2-methyl-4-oxo-2H-1,2-benzothiazine 1,1-dioxide)]-A novel product derived from piroxicam

A novel compound, spiro[(2,3-dihydro-2-oxo-imidazo[1,2-a]pyridine)-3,3-(3,4-dihydro-2-methyl-4-oxo-2H-1,2-benzothiazine 1,1-dioxide)] (3) , was isolated during an attempt to convert 4-hydroxy-2-methyl-N-(2-pyridinyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide ( 1 ) (Piroxicam) to an O-trifluoromethanesulfonyl ester. A possible mechanism is offered to explain this unusual transformation.     

Functionalization of substituted 2(1H)- and 4(1H)-pyridones. III. The preparation of substituted 6-Vinyl-1,2-dihydro-2-oxo- and 1,4-dihydro-4-oxo-3-pyridinecarboxylic acids through the chemistry of pyridone dianions

The synthesis of various substituted 6-vinyl-1,2-dihydro-2-oxo-3-pyridinecarboxylic acids from the dianions of 1,2-dihydro-6-methyl-2-oxo-3-pyridinecarbonitrile and the corresponding 3-t-butyl ester is reported. The dianions were generated with LDA in THF at low temperature and reacted with various carbonyl substrates. Several conditions for the dehydration and hydrolysis of these adducts to the vinyl pyridone acids are discussed. Employing the conditions used for the 2-pyridone analogs, a series of substituted 6-vinyl-1,4-di-hydro-4-oxo-3-pyridinecarboxylic acids was prepared through the new dianion of 1,4-dihydro-6-methyl-4-oxo-3-pyridinecarboxylic acid, t-butyl ester.     

Ring opening reactions of 6-oxo-substituted spiro-pyrrolidinediones: Synthesis of 4-substituted-1,5-dihydro-3-hydroxy-2-oxo-1,5-diphenyl-2H-pyrroles

Reaction of 2-oxocylalkaneglyoxylate esters with N-phenylmethyleneaniline yields spiro compounds such as 2-aza-3,4,6,-trioxo-1,2-diphenylspiro[4.4]nonane 4 and cycloalkane-2-aza-3,4,6-trioxo-1,2-diphenylspiro-[4.5]decanes 5–7 . These undergo solvolytic opening of the the oxocycloalkane ring to yield 4-substituted-1,5-dihydro-3-hydroxy-2-oxo-1,5-diphenyl-2H-pyrroles 12–17 .     

Functionalization of substituted 2(1H)-pyridones. V. The synthesis of 1,2-dihydro-2-oxo-3,5-pyridinedicarboxylic acid derivatives through a novel dianion route

A new pyridone dianion was prepared by halogen-metal exchange from 5-bromo-1,2-dihydro-2-oxo-3-pyrid-inecarboxylic acid, t-butyl ester and two equivalents of n-butyllithium. This 1,5-dianion readily reacted at C₅ with electrophiles. Quenching with carbon dioxide gave the previously unreported 1,2-dihydro-2-oxo-3,5-pyridine dicarboxylic acid, 3-t-butyl ester. The 5-carboxyl groups were selectively converted to the ethyl ester and the ethyl amide through the 5-imidazolide. The 3-t-butyl ester was easily removed from all derivatives with acid hydrolysis.     

A convenient synthesis of 3-alkyl-2,3-dihydro-2,4-dioxo-6-phenyl-, 3-alkyl-2,3-dihydro-4-oxo-6-phenyl-2-thioxo-, and 3-alkyl-2-arylimino-2,3-dihydro-4-oxo-6-phenyl-4H-1,3-thiazines

The reactions of 1-alkylamino-1-alkylthio-3-phenylpropene-3-thiones 3 with thiophosgene and phosgene in toluene, followed by treatment of the reaction mixture with triethylamine gave 3-alkyl-2,3-dihydro-4-oxo-6-phenyl-2-thioxo- 4 , 3-alkyl-2,3-dihydro-2,4-dioxo-6-phenyl-4H-1,3-thiazines 5 , respectively in good to excellent yields. Similarly treatment of compounds 3 with N-arylimidoyl dichloride in benzene at room temperature gave 3-alkyl-2-arylimino-2,3-dihydro-4-oxo-6-phenyl-4H-1,3-thiazines 6 in excellent yields. The reactions of compounds 3 with oxalyl chloride in toluene gave also 5 in good yields.     

Synthesis of 6-amino-2-aryl-1,2-dihydro-3H-pyrido[2,3-d]pyrimidin-4-one derivatives

This paper reports the synthesis of new pyrido[2,3-d]pyrimidin-4-one derivatives as diuretic agents. Starting with 1,2-dihydro-5-nitro-2-oxo-3-pyridinecarboxylic acid 1 , ethyl 2-ethoxy-5-nitro-3-pyridincarboxylate 4 was obtained. Compound 4 reacts with ammonia, methylamine or S-methylpseudothiourea to give the respective 2-amino-5-nitro-3-pyridinecarboxamide derivatives 5 and 6 or 2-methylthio-6-nitro-3H-pyrido[2,3-d]pyrimidin-4-one 8. Treating carboxamide 5 with arylaldehydes and zinc dichloride, new 2-aryl-1,2-dihydro-6-nitro-3H-pyrido[2,3-d]pyrimidin-4-ones 9 were synthetised. These compounds reduced with iron(II) hydroxide gave 6-amino-2-aryl-1,2-dihydro-3H-pyrido[2,3-d]pyrimidin-4-ones 10 as expected.     

Ethyl 5-amino-3-oxo-1,2-dihydro-1H-pyrazole-1-carboxylate in the selective synthesis of partially hydrogenated pyrazolo[3,4-b]pyridin-3-ones

Ethyl 5-amino-3-oxo-1,2-dihydro-1H-pyrazole-1-carboxylate undergoes selective cyclocondensation with 1,3-dicarbonyl compounds or their synthetic equivalents to give ethyl 3-oxo-1,2-dihydro-pyrazolo[3,4-b]pyridine-1-carboxylates which are readily converted to their 1-unsubstituted analogs.     

Syntheses of 10-Oxo-10H-pyrido[1,2-a]thieno[3,4-d]pyrimidines and 10-Oxo-10H-pyrido[1,2-a]thieno[3,2-d]pyrimidines from methyl tetrahydro-4-oxo-3-thiophenecarboxylate and methyl tetrahydro-3-oxo-2-thiophenecarboxylate,respectively

A general synthesis of 10-Oxo-10H-pyrido[1,2-a]thieno[3,4-d]pyrimidines and 10-Oxo-10H-pyrido[1,2-a]-thieno[3,2-d]pyrimidines is described. Methyl tetrahydro-4-oxo-3-thiophenecarboxylate ( 13 ) was condensed with 6-aminonicotinic acid ( 18 ) to give 3,10-dihydro-10-oxo-1H-pyrido[1,2-a]thieno[3,4-d]pyrimidine-7-carboxylic acid ( 19 ). Treatment of 19 successively with chlorotrimethylsilane, N-chlorosuccinimide and water gave 10-oxo-10H-pyrido[1,2-a]thieno[3,4-d]pyrimidine-7-carboxylic acid ( 17 ). Methyl tetrahydro-3-oxo-2-thiophenecarboxylate ( 21 ) was converted to 10-oxo-10H-pyrido[1,2-a]thieno[3,2-d]pyrimidine-7-carboxylic acid ( 25 ) by an analogous route.     

Studies on quinoline derivatives and related compounds. 1. A new synthesis of 1-alkyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids

A novel preparative method for 1-alkyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids was developed. The key process is the cyclization of N-alkylanilinomethylenemalonales, which was effected successfully in the presence of polyphosphoric acid, polyphosphate ester, boron tri-fluoride or a mixture of acetic anhydride and sulfuric acid. With phosphorus oxychloride, N-alkylanilinomethylenemalonates yielded 1-alkyl-4-chloro-3-carbethoxyquinolinium salts which were hydrolyzed readily to ethyl 1-alkyl-1,4-dihydro-4-oxo-3-quinolineearboxylates or their acids. By means of this novel method several new 1-alkyl-1,4-dihydro-4-oxo-3-quinolineearboxylic acids were prepared.     

Efficient synthesis of functionalized spiro-2,5-dihydro-1,2-λ-oxaphospholes

The reaction of ethyl propiolate with triphenylphosphine (Ph₃P) in the presence of N-alkylisatins led to ethyl 2,2,2-triphenyl-2,5-dihydro-1,2-λ⁵-oxaphosphole-4-carboxylate-spiro-1-alkyl-1,3-dihydro-2H-indol-2-ones in good yield. The reaction of dialkyl acetylenedicarboxylates with Ph₃P in the presence of N-alkylisatins led to dialkyl 2,2,2-triphenyl-2,5-dihydro-1,2-λ⁵-oxaphosphole-3,4-dicarboxylate-spiro-1-alkyl-1,3-dihydro-2H-indol-2-ones and alkyl 4-(alkoxy)-5-oxo-2,5-dihydro-3-furancarboxylate-spiro-1-alkyl-1,3-dihydro-2H-indol-2-ones.     

ZnO nanorods catalyzed <Emphasis Type="Italic">N</Emphasis>-alkylation of piperidin-4-one, 4(3<Emphasis Type="Italic">H</Emphasis>)-pyrimidone,and ethyl 6-chloro-1,2-dihydro-2-oxo-4-phenylquinoline-3-carboxylate

An efficient ligand-free cross-coupling reaction of 2-chloro-3-(chloromethyl)benzo[h]quinoline with N-heterocycles such as piperidin-4-one, 4(3H)-pyrimidone, and ethyl 6-chloro-1,2-dihydro-2-oxo-4-phenylquinoline-3-carboxylate using a catalytic amount of ZnO nanorods as a recyclable catalyst and KOH as the base in DMSO under reflux at 110°C is reported.     

Five-membered 2,3-dioxo heterocycles: LXXIV. Recyclization of 3-aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones by the action of benzohydrazides. Crystalline and molecular structure of N-[2,4-dihydroxy-5-oxo-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)-2-phenyl-2,5-dihydro-1H-pyrrol-1-yl]benzamide

Recyclization of 3-aroyl-1H-pyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones by the action of benzoic acid hydrazides gave N-[2,4-dihydroxy-5-oxo-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)-2-aryl-2,5-dihydro-1H-pyrrol-1-yl]benzamides whose structure was proved by X-ray analysis.     

Synthesis and evaluation of novel 2-oxo-1,2-dihydro-3-quinolinecarboxamide derivatives as serotonin 5-HT4 receptor agonists

A series of N-azabicycloalkyl-1-alkyl-2-oxo-1,2-dihydro-3-quinolinecarboxamides were synthesized and tested for serotonin 5-HT4 receptor-stimulating effects in the regulation of electrically-evoked contraction in guinea pig muscle. Among them, N-azabicycloalkyl-1-isopropyl-2-oxo-1,2-dihydro-3-quinolinecarboxamide (8c, 9c, 10c, 11c, 12c) exhibited potent serotonin 5-HT4 receptor-stimulating activity. The most potent compound, N-(endo-8-methyl-8-azabicyclo[3.2.1 oct-3-yl)-1-isopropyl-2-oxo-1,2-dihydro-3-quinolinecarboxamide (8c, ED50 = 36.3 nMi), was seven times as active as cisapride, while 8c had no affinity for 5-HT1A, 5-HT1D, D2, muscarinic M2 or muscarinic M3 receptors even at 10 microM. Compound 8c stimulated digestive tract motility in conscious fed dogs (1.0 mg/kg p.o.).     

4-hydroxy-2-quinolones 151. Reaction of 4-chloro-3-ethoxycarbonyl-2-oxo-1,2-dihydroquinolines with p-toluenesulfonylhydrazide

The reaction of ethyl 4-chloro-1-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylate with p-toluene-sulfonylhydrazide at room temperature in the system DMSO/K₂CO₃ gives 5-methyl-2-(toluene-4-sulfonyl)-1,2-dihydro-5H-pyrazolo[4,3-c]quinoline-3,4-dione, alkylation of which using ethyl iodide gives the 1N-substituted derivative. For Communication 150 see [1]. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 59-66, January, 2009.     

Recyclization of ethyl 1-alkyl-5-benzoyl-6-methylsulfanyl-2-oxo-1,2-dihydropyridine-3-carboxylates into Bicyclic <Emphasis Type="Italic">N</Emphasis>-alkyl-5-benzoyl-2-oxo-1,2-dihydropyridine-3-carboxamide derivatives by the action of nitrogen-containing 1,4- and 1,5-binucleophiles

Reactions of ethyl 1-alkyl-5-benzoyl-6-methylsulfanyl-2-oxo-1,2-dihydropyridine-3-carboxylates with nitrogen-containing 1,4- and 1,5-binucleophiles (o-phenylenediamine, o-aminobenzenethiol, ethane-1,2-diamine, and propane-1,3-diamine) involved recyclization, leading to the formation of fused N-alkyl-5-benzoyl- 2-oxo-1,2-dihydropyridine-3-carboxamides, diethyl 6,6′-oxybis(1-alkyl-5-benzoyl-2-oxo-1,2-dihydropyridine-3-carboxylates), and diethyl 6,6′-[ethane-1,2-diyl(or propane-1,3-diyl)diimino]bis(1-alkyl-5-benzoyl-2-oxo-1,2-dihydropyridine-3-carboxylates), depending on the reactant ratio. The sequence of formation of intermediate recyclization products was determined.     

Synthesis of 2-substituted 4,5-dihydro-4-oxo-3-furancarboxylates using acylative intramolecular cyclization of sulfonium salts

A simple and efficient synthesis of 4,5-dihydro-4-oxo-3-furancarboxylates using an acylative intramolecular cyclization of sulfonium salts is described. The reaction involved the efficient formation of a mixed anhydride between a linear carboxylic acid and trifluoroacetic anhydride in the presence of N-methylimidazole, followed by the sequential conversion into a highly reactive acylammonium species in situ. This procedure is easily handled, uses readily available inexpensive reagents, and provides a variety of 2-substituted 4,5-dihydro-4-oxo-3-furancarboxylates.     

Reaction of 2-dimethylaminomethylene-1,3-diones with dinucleophiles. V. Synthesis of 5-acyl-1,2-dihydro-2-oxo-3-pyridinecarbonitriles and 1,2,5,6,7,8-hexahydro-2,5-dioxo-3-quinolinecarboxamides

The reaction of open-chain sym-2-dimethylaminomethylene-1,3-diones Ia-d with sodium cyanoacetamide gave, generally in good yields, 6-substituted 5-acyl-1,2-dihydro-2-oxo-3-pyridinecarbonitriles IIa-d, whereas cyclohexane sym-2-dimethylaminomethylene-1,3-diones Ie-h afforded in general a mixture of 1,2,5,6,7,8-hexahydro-2,5-dioxo-3-quinolinecarbonitriles and 5,6,7,8-tetrahydro-2,5-dioxo-2H-1-benzopyran-3-carboxamides, the latter being isolated in two cases. The reaction of Ie-h with cyanoacetamide in refluxing anhydrous ethanol gave 1,2,5,6,7,8-hexahydro-2,5-dioxo-3-quinolinecarboxamides IIIe-h in excellent yields, whereas Ia-d did not react with the exception of Ia which afforded in good yield 3-pyridinecarboxamide IlIa. Other 3-pyridine-carboxamides were obtained by partial hydrolysis of nitriles IIb,d. 3-Pyridine and 3-quinoline carboxamides were hydrolyzed in satisfactory yields with hydrochloric acid to the corresponding carboxylic acids, which were decarboxylated in good yields to 5-acyl-2(1H)-pyridinones and 7,8-dihydro-2,5(1H,6H)-quinolinediones, respectively, by reflux in quinoline containing a catalytic amount of copper powder.     

Synthesis of 2-(5-aryl-4-methyl-2-oxo-1,2-dihydro- 3<Emphasis Type="Italic">H</Emphasis>-pyrrol-3-ylidene)malononitriles

4-Oxoalkane-1,1,2,2-tetracarbonitriles in the presence of an equimolar amount of morpholine were converted to previously unknown 2-(5-aryl-4-methyl-2-oxo-1,2-dihydro-3H-pyrrol-3-ylidene)malononitriles.     

A new ring transformation: Synthesis of 5,5-dimethyl-3-oxo-1-pyrroline 1-oxides from 6,6-dimethyl-4-oxo-5,6-dihydro-1,2,4h-oxazines

The nitrosation of some γ,δ-unsaturated β-diketo compounds affords the 3-substituted 4-oxo-5,6-dihydro-1,2,4H-oxazines. These compounds are converted to the isomeric 3-oxo-1-pyrroline 1-oxides by a facile thermal rearrangement.     

Studies on chemotherapeutics I. Synthesis of 5-substituted-4-oxo-1,4-dihydro-3-pyridinecarboxylic acid derivatives

Ethyl 5-substituted-4-oxo-1,4-dihydro-3-pyridinecarboxylates were synthetized by reacting 1,3,5-triazine with 4-substituted ethyl acetoacetate derivatives in ethanol, in the presence of sodium ethoxide. The l-alkyl-5-substituted-4-oxo-1,4-dihydro-3-pyridinecarboxylic acids required for the antimicrobial studies were prepared by N-alkylation (with triethyl phosphate or alkyl halides) and alkaline hydrolysis of the pyridone esters.