Synthesis of 11-aza-5H-benzophenoxazin-5-one and 11-Aza-5H-pyridophenoxazin-5-one derivatives

The 1,6-disubstituted- and 4,6-disubstituted-11-aza-5H-benzo[a]phenoxazin-5-one as well as 6-substituted-11-aza-5H-pyrido[a]phenoxazin-5-one derivatives were prepared by the condensation of 2-amino-3-hydroxypyridine with 5-substituted-2,3-dihalogeno-1,4-naphthoquinones and 6,7-dibromo-5,8-quinolinequinone respectively. The resulting compounds were subjected to reduction, acetylation, dehalogenation and reaction with aniline.     

A new method for the synthesis of 6H,11H-indolo[3,2-c]-isoquinolin-5-ones/thiones and their reactions

The synthesis of 8-substituted and unsubstituted 6H,11H-indolo[3,2-c]isoquinolin-5-ones/thiones 3a-c and 4a-c and their derivatives viz, ethyl (8-substituted-6H,11H-indolo[3,2-c]isoquinolin-5-on-6-yl)acetates 5a-c , (8-substituted-6H,11H-indolo[3,2-c]isoquinolin-5-on-6-yl)acetyl hydrazides 6a-c , 3,5-disubstituted-pyrazoles 7a-c and 8a-c , 3-substituted-pyrazol-5-ones 9a-c and 5-(8-substituted-6H,11H-indolo[3,2-c]isoquinolin-5-on-6-yl)methyl-1,3,4-oxadiazole-2-thiones 10a-c , also ethyl (8-substituted-11H-indolo[3,2-c]isoquinolin-5-ylthio)ace-tates 11a-c , (8-substituted-11Hindolo[3,2-c]isoquinolin-5-ylthio)acetyl hydrazides 12a-c , 3,5-disubstituted-pyrazoles 13a-c and 14a-c , 3-substituted-pyrazol-5-ones 15a-c and 5-(8-substituted-11H-indolo[3,2-c]isoquin-olin-5-yl)thiomethyl-1,3,4-oxadiazole-2-thiones 16a-c is described.     

Nitrosation of methyl 2-acylamino-3-dimethylaminopropenoates. A simple conversion of n-acylglycines into 5-substituted 1,2,4-Oxadiazole-3-carboxylates

A novel simple synthesis of 5-substituted-1,2,4-oxadiazole-3-carboxylates 5 from N-acylglycines 1 , which are transformed with DMF in the presence of phosphorus oxychloride into 2-substituted-4-dimethyl-aminomethyleneoxazol-5(4H)-ones 2 , followed by opening into 2-aroylamino-3-dimethylamino-propenoates 3 , and nitrosation to give the oximes 4 as intermediates, which cyclize spontaneously into 5-substituted-1,2,4-oxadiazole-3-carboxylates 5 . The compounds 2 can be transformed into 5 without isolation of 3 and 4 .     

Formation of 5-aroyl-3-(2H)isothiazolones from the reaction of 3-aroylpropionamides with thionyl chloride

Reaction of N-substituted-3-aroylpropionamides with excess thionyl chloride was found to give sulfur-nitrogen heterocyclic compounds, which were characterized as 2-substituted-5-aroyl-3-(2H)isothiazolones.     

Synthesis and structural studies of mono- and bis-n 5-cyclopentadienyl)hafnium(IV) derivatives of heterocyclic thioketones

Summary The reactions of dichlorobis(n ⁵-cyclopentadienyl)hafnium(IV) with four different classes of heterocyclic thioketoneviz., 3-substituted-4-amino-S-triazole-5-thiol, 1-substituted-2-thiohydantoin, 5-substituted 1, 3, 4-oxadiazole-2-thione and 1-substituted tetrazoline-5-thione were studied in anhydrous tetrahydrofuran in the presence of base. The reaction products were characterized on the basis of elemental analyses, electrical conductance, magnetic susceptibility and spectral (electronic, infrared and¹H n.m.r.) data.     

A Coupling Reaction of 4-Amino-5-mercapto- 3-substituted-1,2,4-triazoles to Generate Symmetrically Substituted Hydrazines

Summary. A novel coupling reaction of 4-amino-5-mercapto-3-substituted-1,2,4-triazoles to generate symmetrically substituted hydrazines, N,N′-bis(5-mercapto-3-substituted-1,2,4-triazol-4-yl)hydrazines was unexpectedly observed. Five examples are presented to demonstrate this reaction. All isolated products were unambiguously characterized.     

Synthesis and mass spectral studies of 1-[5-chloro-1-substituted-2(1H)-pyrazin-2-on-3-yl]-5-aryl-3-methylpyrazoles

Sixteen new 1-[5-chloro-1-substituted-2(1H)-pyrazin-2-on-3-yl]-5-aryl-3-methylpyrazoles V have been synthesized by condensation of 5-chloro-1-substituted-3-hydrazino-2(1H)-pyrazin-2-ones III and 1-aryl-1,3-butanediones IV in dry 1,4-dioxane. The general mass spectral fragmentation mode of these compounds has been studied.     

Synthesis of the 5H-pyrrolo[2,1-a]isoindole ring with 1,3-dipolar cycloaddition reactions

The 1,3-dipolar cycloaddition reaction between mesoionic oxazolines, formed from either 1,3-dihydro-2-substituted-2H-isoindole-1-carboxylic acids or 1,3-dihydro-1-oxo-α-substituted-2H-isoindole-2-acetic acids, and dimethylacetylene dicarboxylate has led to the synthesis of several 5H-pyrrolo[2,1-a]isoindole derivatives 9a-d .     

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.     

A highly enantioselective synthesis of 5-(l-menthyloxy )-4-substituted-3-chloro-2(5H )-furanones

In this paper, stereocontrolled tandem Michael addition-elimination reaction of the novel chiral source, 5-(l-menthyloxy)-3,4-dichloro-2(5H)-furanone, with various thiols and amines has been investigated. A series of new enantiomerically pure compounds, 5–(l-menthyloxy)-4-substituted-3-chloro-2(5H)-furanones, were obtained in good yields with d. e. ? 98% under mild conditions.     

Synthesis of benzophenothiazinone derivatives from 2,3,5-trisubstituted-1,4-naphthoquinones with 2-aminothiophenol

The 1-substituted-5H-benzo[2,3-a]phenothiazin-5-one, 4-substituted-5H-benzo[6,5-a]phenothiazin-5-one and 6-substitutedbenzo[a][1,4] benzothiazino[3,2-c]phenothiazine derivatives were prepared by the condensation of 5-substituted-2,3-dichloro-1,4-naphthoquinones with 2-aminothiophenol. Reduction, acetylation and dehalogenation of the resulting compounds were carried out and the structures of the products were inferred from comparison with the authentic compound.     

Synthesis of isomeric N-substituted 5-methyl-2H-1,2,6-thiadiazin-3(6H)one 1,1-dioxides from sulfamides and diketene

The reaction of N-n-butyl and N-benzylsulfamides with diketene in acetic acid solution in the presence of mercuric cyanide as a catalyst, afforded the corresponding 5-methyl-2-substituted-2H-1,2,6-thiadiazin-3(6H)one 1,1-dioxides. The reaction of the above mentioned sulfamides with diketene in an aqueous alkaline medium resulted in the isolation of the corresponding N-aceto-acetyl-N' -substituted-sulfamides, which were then converted into 5-methyl-6-substituted-2H-1,2,6-thiadiazin-3(6H)one 1,1-dioxides. Catalytic hydrogenation of the 5-methyl-2- and 6-n-butyl-2H-1,2,6-thiadiazin-3(6H)one 1,1-dioxides furnished the corresponding dihydro-derivatives. The structures of the isomeric 1,2,6-thiadiazine 1,1-dioxide derivatives obtained were assigned on the basis of nmr spectroscopic studies.     

Facile Synthesis of Alkyl and Aryl Substituted Dibenzo[b,g][1,8]naphthyridin-5-ones

The reaction of 2,4-dichloroquinolines with o-aminoacetophenone and o-aminobenzophenone under neat conditions yielded 2′-acetyl and 2′-benzoyl substituted-4-chloro-2-(N-phenylamino)quinolines, respectively, which on treatment with sodium methoxide afforded the 2′-substituted-4-methoxy-2-(N-phenylamino)quinolines. These potential intermediates, on polyphosphoric acid–catalyzed cyclization at two different temperatures, gave the respective 6-methyl and 6-phenyl substituted dibenzo[b,g][1,8]naphthyridin-5-ones. These temperature differences for the formation of the final products were due to the in situ formation of the respective 2′-substituted-2-(N-phenylamino)quinolin-4-ones from the chloro and methoxy intermediates. The naphthyridin-5-ones were subjected to N-methylation, where the methyl group in the 1-position was found to hinder the reaction sterically, consequently increasing the reaction time to more than that of the other derivatives.     

Synthesis of 4H-pyrazolo- and 4H-pyrrolophenothiazin-4-one derivatives

5-Methyl- and 6-methyl-2-phenyl-2H-indazole-4,7-diones were condensed with 2-aminobenzenethiol or 6-substituted-3-aminopyridine-2(1H)thiones 4 to produce a new type of 5-methyl-2-phenyl-4H-pyrazolophenothiazin-4-ones or 8-substituted-7-aza-5-methyl-2-phenyl-4H-pyrazolophenothiazin-4-one derivatives. From 6-bromo-2,5-dimethyl-1,3-diphenyl-2H-isoindole-4,7-dione and 4 8-substituted-7-aza-2,5-dimethyl-1,3-diphenyl-4H-pyrrolophenothiazin-4-one derivatives were also prepared.     

Studies on chemotherapeutics III. Synthesis and cyclisation of 5-substituted-4-oxo-1,4-dihydro-3-pyridinecarbonyl-semicarbazide and- thiosemicarbazide

1,4-Disubstituted-semicarbazide and thiosemicarbazide derivatives were synthetized from 5-substituted-4-oxo-1,4-dihydro-3-pyridinecarbohydrazides and cyclized to 3-mercapto-4H-1,2,4-triazoles. The obtained compounds could be S-methylated with methyl iodide in methanol. The new compounds were tested for antibacterial and antifungal activities.     

Studies on pyridonecarboxylic acids . 2. Synthesis and antibacterial activity of 8-substituted-7-fluoro-5-oxo-5H-thiazolo[3,2-a]quinoline-4-carboxylic acids

A series of 8-substituted-7-fluoro-5-oxo-5H-thiazolo[3,2-a]quinoline-4-carboxylic acids was prepared and evaluated for antibacterial activity. These compounds were synthesized from ethyl 2-mercaptoquinoline-3-carboxylates 17 which were obtained from anilines 11 by a route involving an intramolecular cyclization reaction.     

From Levulinic Acid to Biheterocycles: Synthesis of 1-[(5-Hydroxy-5-trifluoromethyl-3-substituted-4,5-dihydro-1H-pyrazol-1-yl)-3-(5-trifluoromethyl-1H-pyrazol-3-yl)propan-1-ones

We develop an efficient method to synthesize novel propionyl-spaced bisheterocyclic compounds. It entails cyclocondensation of 3-(5-trifluoromethyl-1H-pyrazol-3-yl)propanoyl hydrazide obtained from levulinic acid, with 1,1,1-trifluoro-4-methoxy-3-alken-2-ones proceeding regiospecifically to 1-[(5-trifluoromethyl-5-hydroxy-3-substituted-4,5-dihydro-1H-pyrazol-1-yl)-3-(5-trifluoromethyl-1H-pyrazol-3-yl)propan-1-one derivatives.     

Nitrosation of methyl 2-cinnamoylamino-3-dimethylaminopropenoates. Alkyl N-cinnamoyloxalic acid hydroxyimidic amides,intermediates in the synthesis of alkyl 5-styryl-1,2,4-oxadiazole-3-carboxylates

Alkyl 2-(substituted cinnamoylamino)-3-dimethylaminopropenoates 5, prepared either from glycine ( 1 ) and substituted cinnamoyl chlorides 2 via oxazol-5(4H)-ones 4 , or from cinnamoylglycinate with t-butoxy-bisdimethylaminomethane, were transformed by nitrosation into 5-substituted-1,2,4-oxadiazole-3-carboxylates 8 . The formation of alkyl N-cinnamoyloxalic acid hydroxyimidic amides 7, which were isolated as intermediates, represent a novel synthesis of N-acyl substituted hydroxyimidic amides.     

The transformations of 4-heteroarylaminomethylene-5(4H)-oxazolones into dehydropeptide derivatives

2-Phenyl-4-heteroarylaminomethylene-5(4H)-oxazolones 3 , which were prepared from the corresponding N,N-dimethyl-N'-heteroarylformamidines 1 and hippuric acid 2 in acetic anhydride, react with amino acids giving dehydropeptide derivatives 4, 5 , and 6 as products. Dehydration of N-protected peptides 7–10 , containing glycine at the C-terminal, followed by the reaction with formamidines 1 gave 2-substituted-4-heteroarylaminomethylene-5(4H)-oxazolones 11–14 .     

Synthesis of 4,7-dihydro-4-oxoisoxazolo[5,4-b]pyridine-5-carboxylic acid derivatives as potential antimicrobial agents

Synthetic approaches to 3-substituted-7-ethyl-4,7-dihydro-4-oxoisoxazolo[5,4-b]pyridine-5-carboxylic acid derivatives from 3-substituted-5-aminoisoxazoles are reported.