Simple procedure for preparation of quinoxalin-2(1H)-one 3-[Oxo(cyclo)alkyl(idene)] derivatives

A simple preparative procedure was developed for 3-(2-oxoalkylidene)-3,4-dihydroquinoxalin-2(1H)-ones, 4,5-dihydroxy-1-[3-oxo-3,4-dihydroquinoxalin-2(1H)-ylidene]-3,5-octadiene-2,7-dione, and 3-(2,3-dihydroxy-4-methyl-5-oxo-1,3-cyclopentadien-1-yl)quinoxalin-2(1H)-one by reaction of methyl ketones first with diethyl oxalate in the presence of sodium, and then with o-phenylenediamine.     

Rearrangements of N-alkyl-/aryl-nitrones derived from 4-oxo-4H-1-benzopyran-3-carboxaldehyde--a solvent-dependent process

C-(4-Oxo-4H-1-benzopyran-3-yl)-N-alkyl-/aryl-nitrones derived from 4-oxo-4H-1-benzopyran-3-carboxaldehyde, rearrange to 2-alkyl-/aryl-amino-3-formylchromone and/or 3-(alkyl-/aryl-aminomethylene)chroman-2,4-dione depending upon the reaction medium. 3-(Alkylaminomethylene)chroman-2,4-dione has been utilized in the synthesis of 1-benzopyrano[3,4-d]isoxazole-4-one.     

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 new thietanylpyrimidine and thietanylimidazole derivatives

New thietanyl-substituted derivatives of pyrimidine-2,4(1H,3H)-dione and imidazole were synthesized. The alkylation of 6-methylpyrimidine-2,4(1H,3H)-diones with 2-chloromethylthiirane in water involved the N¹ atom of the pyrimidine ring and afforded 6-methyl-1-(thietan-3-yl)-pyrimidine-2,4(1H,3H)-diones. Under analogous conditions 6-aminopyrimidine-2,4(1H,3H)-dione gave rise to 6-(thietan-3-ylamino)pyrimidine-2,4(1H,3H)-dione. Unsymmetrically substituted 2-methyl-4(5)-nitro- and 5(4)-bromo-2-methyl-4(5)-nitro-1H-imidazoles reacted with 2-chloromethylthiirane to produce mixtures of isomeric 2-methyl-4(5)-nitro-1-(thietan-3-yl)-1H-imidazoles and 5(4)-bromo-2-methyl-4(5)-nitro-1-(thietan-3-yl)-1H-imidazoles.     

Transformations of 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one under various conditions of cyclopropyldiazonium generation

Cyclopropyldiazonium generated by basic decomposition of N-cyclopropyl-N-nitrosourea easily entered into an azo coupling reaction with 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one (2) to give the corresponding cyclopropylhydrazone in up to 90% yield. Competitive processes occurring under the conditions of cyclopropyldiazonium generation by nitrosation of cyclopropylamine with butyl nitrite mainly include nitrosation of the starting pyrazolone 2. Subsequent transformations of the resulting heterocyclic 3-methyl-1-phenyl-1H-pyrazole-4,5-dione 4-oxime yield 4-[cyclopropyl(oxido)imino]-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2151–2155, December, 2006.     

Hydrolytic opening of the quinazoline ring in 3-furfuryl-4-oxo-3,4-dihydroquinazoline derivatives

Ethyl 3-furfuryl-4-oxo-3,4-dihydroquinazoline-2-carboxylate extremely readily undergoes hydrolysis in acid, alkaline, or neutral medium with formation of 2-(2-ethoxy-1,2-dioxoethylamino)-N-furfurylbenzamide. The reaction of ethyl 3-furfuryl-4-oxo-3,4-dihydroquinazoline-2-carboxylate with phenylmagnesium bromide yields N-furfuryl-2-(2-hydroxy-2,2-diphenyl-1-oxoethylamino)benzamide as a result of hydrolytic cleavage of the quinazoline ring.     

Synthesis of 3-(aminooxoethyl)-6-methyl-1-(thiethan-3-yl)-pyrimidine-2,4-(1H,3H)-diones

A new approach to prepare 2-chloroacetamides has been developed, based on the reaction of chloroacetyl chloride with excess of secondary amines. Alkylation of 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1H,3H)-dione with the synthesized 2-chloroacetamides in the presence of potassium carbonate has afforded N ³-acetamido-substituted 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1H,3H)-diones.     

Aminomethylation of 6-methyl-1-(thietan-3-yl)pyrimidine-2,4(1H,3H)-dione

Mannich reactions of 6-methyl-1-(thietan-3-yl)pyrimidine-2,4(1H,3H)-dione with formaldehyde and morpholine, piperidine, N-methylpiperazine, and diethylamine gave the corresponding 5-aminomethylsubstituted pyrimidine derivatives. The title compound reacted with excess piperazine to form 3,5-bis-(piperazin-1-yl) derivative, while its reaction with an equimolar amount of piperazine afforded 5,5′-(piperazin-1,4-diylbismethylene)bis[6-methyl-1-(thietan-3-yl)pyrimidine-2,4(1H,3H)-dione].     

Rearrangement of 1,4-benzodiazepin-2,4-diones to 3,l-benzoxazin-4-ones

Treatment of 7-chloro-3,4-dihydro-1H-1,4-benzodiazepin-2,5-dione (Ia) with refluxing acetic anhydride in the presence of pyridine afforded 6-chloro-2-methyl-4H-3,1-benzoxazin-4-one (IIa). A plausible reaction path for this novel rearrangement reaction is described: Ia → 4-acetyl-7-chloro-3,4-dihydro-lH-1,4-benzodiazepin-2,5-dione → 7-chloro-1,4-diacetyl-3,4-dihydro-lH-1,4-benzodiazepin-2,4-dione → IIa. When 7-chloro-3,4-dihydro-4-methyl-lH-1,4-benzodiazepin-2,5-dione (Ib), 3,4-dihydro-4-methyl-1H-1,4-benzodiazepin-2,5-dione (Id) and 3,4-dihydro-1-methyl-1H-1,4-benzodiazepin-2,5-dione (Ie) were allowed to react with acetic anhydride under conditions similar to those used for the rearrangement reaction, only acetylation occurred.     

Products from furans. VI. Synthesis of dihydro-2-disubstituted-2H-pyran-3(4H)-ones,tetrahydro-3-(aminomethyl)-2-(p-methoxyphenyl)-2-methyl-2H-pyran-3-ol derivatives and 6-(p-methoxyphenyl -6-methyl-7-oxa-1,3-diazaspiro[4,5]decane-2,4-dione

Hydrogenolysis of 5,6-dihydro-6-(p-methoxyphenyl)-6-methyl-5-oxo-2H-pyran-2-yl ethyl carbonate yielded dihydro-2-(p-methoxyphenyl)-2-methyl-2H-pyran-3(4H)-one, 3 . Subsequently cyanohydrin 4 , derived from 3 , on reduction afforded 3-(aminomethyl)tetrahydro-2-(p-methoxyphenyl)-2-methyl-2H-pyran-3-ol, 5 . The synthesis of N-dimethyl,N-isopropyl,N-imidazolyl as well as N-oxazolinyl derivatives of 5 is presented. The synthesis of 6-(p-methoxyphenyl)-6-methyl-7-oxa-1,3-diazaspiro[4,5]decane-2,4-dione 10 , a spiro hydantoin prepared from ketone 3 is also reported.     

Design and synthesis of novel 5,6-bisindolylpyrimidin-4-ones structurally related to ruboxistaurin (LY333531)

2,3-Bis(1-methyl-1H-indol-3-yl) methyl-3-oxopropionate is a key intermediate in the synthesis of a new family of LY333531 analogues. Base-mediated cyclocondensation with thiourea afforded novel 5,6-bis(1-methyl-1H-indol-3-yl)-2-thioxo-2,3-dihydropyrimidin-4(1H)-one, which was efficiently converted to the pyrimidin-2,4(1H,3H)-dione congener. Synthesis of a six-membered K-252c analogue, 5,6-bis(1-methyl-1H-indol-3-yl)pyrimidin-4(3H)-one, is also described.     

N,N′-Linked 1,2-benzisothiazol-3(2H)-one 1,1-dioxides: synthesis, biological activity, and derived radicals

A number of N,N′-linked benzoannelated isothiazol-3(2H)-one 1,1-dioxides, not available via oxidation of isothiazolium salts, were obtained with good yields by reaction of N-amino heterocycles with 2-chlorosulfonylbenzoyl chloride and evaluated for their inhibitory activity toward human leukocyte elastase (HLE) and acetylcholinesterase (AChE). 2-(Phthalimid-1-yl)-1,2-benzisothiazol-3(2H)-one 1,1-dioxide and 2-(2-methyl-4-oxo-3(4H)-quinazolinyl)-1,2-benzisothiazol-3(2H)-one 1,1-dioxide were found to be inhibitors of HLE and tested as potential precursors of nitrogen-centered radicals using 266 nm laser flash photolysis.     

Isatins 3-C annulation vs ring-opening: Two different pathways for synthesis of spiro compounds via multicomponent reactions

An efficient synthesis of spiro compounds via two different pathways from the reactions of isatins, 3-phenylisoxazol-5(4H)-one (3-ethylisoxazol-5(4H)-one), and pyrazol-5-amine (6-aminopyrimidine-2,4(1H,3H)-dione) were reported. The catalyst Amberlyst-15 could be easy recycled and reused for many time without any appreciable loss in catalytic activity. The new type spiro compounds were gained through the ring-opening of isatins process. The structures of spiro[indoline-3,4′-isoxazolo[5,4-b]pyrazolo[4,3-e]pyridin]-2-one, spiro[isoxazolo[5,4-b]quino line-4,5′-pyrrolo[2,3-d]pyrimidine]-2′,4′,6′(1′H,3′H,7′H)-trione, and spiro[indoline-3,4′-pyrazolo[3,4-b]pyridine]-2,6′(5′H)-dione were successfully confirmed by ¹H NMR, ¹³C NMR, HRMS, and X-ray crystal diffraction analysis.     

Synthesis of 3-amino-3,4-dihydroquinazolin-4-one derivatives from anthranilic acid hydrazide and dicarboxylic acids

Treatment of anthranilic acid hydrazide with 2 equiv of ethoxalyl chloride gave the corresponding diester which underwent cyclization in acetic anhydride to produce ethyl 3-(ethoxalylamino)-4-oxo-3,4-dihydroquinazoline-2-carboxylate. Acylation of anthranilic acid hydrazide first with succinic anhydride and then with ethoxalyl chloride led to the formation of 4-[2-(2-{[ethoxy(oxo)acetyl]amino}benzoyl)hydrazino]-4-oxobutanoic acid whose cyclization in acetic acid afforded N-(2-ethoxycarbonyl-4-oxo-3,4-dihydroquinazolin-3-yl)succinamic acid, while in acetic anhydride ethyl 3-(2,5-dioxopyrrolidin-1-yl)-4-oxo-3,4-dihydroquinazoline-2-carboxylate was obtained. The latter was brought into reactions with amines and hydrazine hydrate and alkaline hydrolysis. Acylation of 2-[2-(2-aminobenzoyl)hydrazinocarbonyl]benzoic acid with ethoxalyl chloride gave ethyl N-[2-(phthalimidocarbamoyl)phenyl]oxamate, and with succinic anhydride, 3-[4-oxo-3-phthalimido-3,4-dihydroquinazolin-2-yl]propionic acid. 4-[2-(2-Aminobenzoyl)hydrazino]-4-oxobutanoic acid reacted with phthalic anhydride in boiling acetic acid to give phthalazino[1,2-b]quinazoline-5,8-dione via elimination of succinic acid residue.     

Synthesis of novel isoxazolines and isoxazoles of N-substituted pyrazolo[3,4-d]pyrimidin-4(5H)-one derivatives through [3+2] cycloaddition

3,6-Dimethyl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-one 3 was prepared by an intramolecular cyclization of N-(4-cyano-3-methyl-1-phenyl-1H-pyrazol-5-yl) acetamide 2 in ethanol in the presence of piperidine. N-allylation and N-propargyl alkylation of N-substituted pyrazolo[3,4-d] pyrimidin-4(5H)-one 3 yielded the corresponding dipolarophiles 4 and 5 which afford by condensation with arylnitrile oxides in toluene the expected new isoxazolines 6 and isoxazoles 7, respectively. On the other hand, the aminopyrazole 1 in refluxing with ethanol in the presence of sodium hydroxide afforded the corresponding carboxamide 8, which then, was converted to its ethyl 3-methyl-4-oxo-1-phenyl-4,5-dihydro-1H-pyrazolo[3,4-d] pyrimidine-6-carboxylate 9 with neat diethyl oxalate. The dipolarophile 10 on regiospecific 1,3-dipolar cycloaddition with arylnitrile oxides affords isoxazoles 11 and the unexpected deethoxycarbonylated isoxazoles 12. The target compounds were completely characterized by ¹H NMR, ¹³C NMR, IR and HRMS.     

Reaction between isocyanides and dialkyl acetylenedicarboxylates in the presence of strong CH-acids: one-pot synthesis of highly functionalized annulated 4H-pyrans

The highly reactive 1:1 adduct, produced from the reaction between dialkyl acetylenedicarboxylates and alkyl isocyanides, was trapped by strong cyclic CH-acids such as 4-hydroxy-6-methyl-2H-pyran-2-one or 4-hydroxycoumarin to yield dialkyl 2-(alkylamino)-5-oxo-4H,5H-pyrano[3,2-c]chromene-3,4-dicarboxylates or dialkyl 7-methyl-2-(alkylamino)-5-oxo-4H,5H-pyrano[4,3-b]pyran-3,4-dicarboxylates in good yields at room temperature.     

Synthesis of certain N- and C-alkyl purine analogs

A number of N- and C-alkyl derivatives of selected guanine analogs have been synthesized as potential antiviral agents. n-Pentyl, n-hexyl and 6-hydroxyhexyl derivatives in the imidazo[1,2-α]-s-triazine, 9–11 , imid-azo[1,2-α]pyrimidine, 13–17 , and thiazolo[4,5-d]pyrimidine, 19–21, ring system have been prepared by the direct alkylation of the sodium salt of the appropriate aglycon with the respective alkylbromides. Dehydra-tive coupling of 3-amino-6-hydrazino-1,2,4-triazin-5(4H)-one ( 22 ) with either hexanoic acid or heptanoic acid, and further ring closure of the reaction products 24a and 24b provided the n-pentyl and n-hexyl derivatives of 6-amino-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H)-one 25a and 25b , respectively. A similar condensation of 3-amino-6-aminomethyl-1,2,4-triazin-5(4H)-one ( 23 ) with heptanoic acid, followed by ring annulation, readily gave 2-amino-7-n-hexylimidazo[5,1-f][1,2,4]triazin-4(3H)-one ( 25c ). Bromination of 25c with N-bromosuccini-mide afforded the corresponding 5-bromo derivative 26 . Alkylation of the in situ generated sodium salt of 4-methoxycarbonylmethyl-5-methoxycarbonyl-2-oxo-1H,3H-imidazole ( 27 ) with 1-bromohexane gave the N-1 alkylated product 31 . Manipulation of the functional groups in 31 and further hydrazine mediated ring annulation furnished 5,6-diamino-1-n-hexyl-3-methylimidazo[4,5-c]pyridine-2,4-dione ( 39 ). Catalytic hydrogena-tion of 39 gave 7-methyl-8-oxo-9-hexyl-3-deazaguanine ( 40 ), a congener of the immunostimulator 7-methyl-8-oxoguanosine.     

Struktur des Hydrazinolyseproduktes von N-(3-Oxo-1-isoindolinyliden)-alanin-äthylester

Hydrazinolysis of N-(3-Oxo-1-isoindolinyliden)alanin Ethyl Ester, Structure of the Product Treatment of N-(3-oxo-1-isoindolinyliden)alanin ethyl ester (6) with hydrazine hydrate leads to 4-methyl-2,3,4,6-tetrahydro[1,2,4]triazino[3,4-a]isoindole-3, 6-dione ( 8 , Scheme 3) and not to the previously postulated 6-hydroxy-2-methyl-2,3-dihydro-imidazo [2,1-a]phthalazin-3-one ( 7 , cf. [2]). The structure of 8 has been established by an independent synthesis as well as by the X-ray analysis of the reaction product 11 from 8 and 3-dimethylamino-2,2-dimethyl-2 H-azirine ( 1 , Scheme 4). A reaction mechanism for the formation of 8 from 6 is suggested in Scheme 5.     

Fluorine-containing 3-arylhydrazono-2,4-dioxobutanoates in reactions with difunctional nucleophiles

3-Arylhydrazono-4-polyfluoroalkyl-2,4-dioxobutanoates reacted with hydrazines to give ethyl 4-aryldiazeno-3-polyfluoroalkyl-1H-pyrazole-5-carboxylates, while analogous reactions of ethyl 3-arylhydrazono-4-pentafluorophenyl-2,4-dioxobutanoates resulted in the formation of 4-aryldiazeno-3-pentafluorophenyl-1,2-dihydropyridazine-5,6-diones or 6-aryl-7,8,9,10-tetrafluoro-2-phenyl-2,4a,6,10b-tetradropyridazo[4,3-c]cinnoline-3,4-diones, depending on the conditions. Cyclocondensation of ethyl 3-arylhydrazono-4-polyfluoroalkyl(or pentafluorophenyl)-2,4-dioxobutanoates with ethylenediamine led to 3-[1-arylhydrazono-2-oxo-2-polyfluoroalkyl(or pentafluorophenyl)ethyl]-5,6-dihydropyrazin-2(1H)-ones, and 3-[1-arylhydrazono-2-oxo-2-polyfluoroalkyl(pentafluorophenyl)ethyl]benzoxazin-2-ones were formed in the condensation with o-aminophenol. Pentafluorophenyl-substituted heterocycles were found to undergo intramolecular ring closure to give 3-hetaryl-substituted 1-aryl-5,6,7,8-tetrafluoro-1,4-dihydrocinnolin-4-ones. The reactions of ethyl 3-arylhydrazono-4-pentafluorophenyl-2,4-dioxobutanoates with o-aminobenzenethiol gave 3-[7-(2-aminophenylsulfanyl)-1-aryl-5,6,8-trifluoro-4-oxo-1,4-dihydrocinnolin-3-yl]benzothiazin-2-ones; 8a-hydroxy-11,12,13,14-tetrafluoro-10-(4-methoxyphenyl)-2,3,4,5,6,7,8a,10-octahydropyrazino[1′,2′:4,5][1,4]diazepino[6,7-c]cinnolin-8-one was isolated in the condensation of ethyl 3-(4-methoxyphenylhydrazono)-4-pentafluorophenyl-2,4-dioxobutanoate with N-(2-aminoethyl)ethane-1,2-diamine.     

Synthesis of 3,3′-(1,6-hexanediyl)bis-pyrimidine derivatives and 3,4-dithia[6.6](1.3)pyrimidinophane

Several 3,3′-(1,6-hexanediyl)bis[6-methyl-2,4(1H,3H)-pyrimidinedione] derivatives ( 4a, 4b , and 4c ) were synthesized from 1,6-(hexanediyl)bis[6-methyl-2H-1,3-oxazine-2,4(3H)-dione] (3) . Compound 4c was converted to 6, which reacted with thiourea giving thiuronium salt 7 . 3,3′-(1,6-Hexanediyl)bis [1-(2-mercaptoethyl)-6-methyl-2,4(1H,3H)-pyrimidinedione] (9) was obtained by the hydrolysis of 7 , and then 9 was oxidized to 12,22-dimethyl-3,4-dithia[6.6] (1.3)-1,2,3,4-tetrahydro-2,4-dioxopyrimidinophane (10) .