Pyrimidine derivatives and related compounds. 38. Synthesis of 1,3-oxazine-2,4-diones and their reaction with nucleophiles. Ring transformation of 1,3-oxazines to pyrimidines

5,6-Unsubstituted 1,3-oxazine-2,4-diones ( 3 ) and 6-unsubstituted 5-methyl-1,3-oxazine-2,4-diones ( 4 ) were prepared by reduction of the corresponding 6-chloro derivatives ( 1 and 2 ). Treatment of 6-chloro-3-methyl-1,3-oxazine-2,4-dione ( 1a ) with sodium azide, sodium cyanide, secondary amines and aniline gave the corresponding 6-substituted compounds ( 7, 9, 10 and 11 ) while the reaction of 1a and 2a,b with primary aliphatic amines such as methylamine and ethylamine caused a ring transformation to pyrimidine ring system giving barbituric acids ( 13a-d ).     

Chemoselective reduction of 3-arylmethylidenetetrahydrofuran-2,4-diones with triethylsilane and sodium cyanotrihydridoborate in acid media

3-Arylmethylidenetetrahydrofuran-2,4-diones were smoothly reduced to the corresponding 3-benzyl derivatives in 50–98% yield with triethylsilane in trifluoroacetic acid or with sodium cyanotrihydridoborate in the system tetrahydrofuran-2 N hydrochloric acid. The reduction of 3-(3-arylprop-2-en-1-ylidene)-tetrahydrofuran-2,4-diones with sodium cyanotrihydridoborate gave 3-cinnamyltetrahydrofuran-2,4-diones as the only products.     

Conventional and microwave-assisted conversion of substituted 3-amino-oxazolidin-2,4-diones into N',N'-disubstituted alpha-hydroxyhydrazides

Substituted 3-amino-oxazolidin-2,4-diones have been prepared by reacting cyanohydrins or alpha-hydroxyesters subsequently with 1,1'-carbonyldiimidazole and 1,1-disubstituted hydrazines followed by acidic hydrolysis in case of the intermediate 3-amino-4-imino-oxazolidin-2-ones. Conventional and microwave-assisted syntheses of N',N'-disubstituted alpha-hydroxyhydrazides have been accomplished by reacting substituted 3-amino-oxazolidin-2,4-diones with catalytic amounts of sodium methoxide in methanol.     

Efficient solid-phase synthesis of quinazoline-2,4-diones with various substituents on aromatic rings

We have developed a method for the solid-phase synthesis of quinazoline-2,4-diones with various substituents on the aromatic ring. Although there have been numerous reports of the solid-phase synthesis of quinazoline-2,4-diones, they were not applicable to the synthesis of the quinazoline-2,4-diones with electron-withdrawing substituents on the aromatic ring. Considering the poor nucleophilicity of the amino group of anthranilic acids, coupling of anthranilic acids to solid-supported amines was investigated without protecting the amino group. Various anthranilamides were prepared using anthranilic acids with electron-withdrawing substituents because a wide range of anthranilic acids are commercially available. These anthranilamides were successfully cyclized with carbonyldiimidazole to give quinazoline-2,4-diones with high purity.     

Annelation of 3,4-dihydroisoquinolines by 3-acyl-5,5-dimethylthiopyran-2,4-diones. Synthesis and properties of 8-aza-17-thia-d-homogona-12,17a-diones

We have used annelation of 3,4-dihydroisoquinolines by 3-acyl-5,5-dimethylthiopyran-2,4-diones to obtain the corresponding 8-aza-17-thia-D-homogonanes, which are novel representatives of heterosteroids. We have studied the tautomerism of 3-acylthiopyran-2,4-diones using NMR spectroscopy and H/D-isotope exchange. We have obtained 2H-isotopomers of 3-acylthiopyran-2,4-diones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1572–1583, October, 2004.     

Synthesis and keto-enol tautomerism of 6-alkyl-1-alkoxypyridine-2,4-diones

Reactions of 2,2-dimethyl-5-(3-oxoalkanoyl)-1,3-dioxane-4,6-diones with alkoxyamines proceed regioselectively at the β′-keto group of the side acyl chain affording the corresponding tricarbonyl imines whose boiling in toluene leads to the formation of products of intramolecular cyclization, N-alkoxy-2,4-dioxopyridine-3-carboxylic acids. The decarboxylition of the obtained pyridine-3-carboxylic acids in mesitylene at 160–165°C gives in the preparative yield N-alkoxypyridine-2,4-diones. Proceeding from the IR and NMR spectra the problems of the keto-enol and imine-enamine tautomerism were discussed for the series of 5-acyl derivatives of the Meldrum acid and the obtained N-alkoxypyridine-2,4-diones.     

Reaction of 3-aminoquinoline-2,4-diones with nitrourea. Synthetic route to novel 3-ureidoquinoline-2,4-diones and imidazo[4,5-c]quinoline-2,4-diones

1-Unsubstituted 3-alkyl/aryl-3-amino-1H,3H-quinoline-2,4-diones react with 1-substituted and 1,1-disubstituted ureas in boiling acetic acid to give 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones. In contrast, the reaction of these amines with nitrourea in dioxane affords novel 3-alkyl/aryl-3-ureido-1H,3H-quinoline-2,4-diones or 9b-hydroxy-3a-alkyl/aryl-3,3a,5,9b-tetrahydro-1H-imidazo[4,5-c]quinoline-2,4-diones, which can smoothly be dehydrated to 3a-alkyl/aryl-3,3a-dihydro-5H-imidazo[4,5-c]quinoline-2,4-diones. All three types of products can be converted to 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones by refluxing in acetic acid.     

SYNTHESIS AND REACTIONS OF 2,3-DIHYDRO- 5-ARYL-5H,6H-THIAZOLO[3,2-b]-2,4-DIAZAFLUORENE-3,6-DIONES OF POTENTIAL BIOLOGICAL ACTIVITIES

Abstract

1,2,3,4-Tetrahydro-l-aryl-3,9-dioxo-2,4-diazafluorenes (2) and 1,2,3,4-tetrahydro-1-aryl-9-oxo-3-thi-oxo-2,4-diazafluorenes (3) were newly synthesized. Compounds 3 reacted with chloroacetic acid, α-bromopropanoic acid, or B-bromopropanoic acid in the presence of fused sodium acetate and acetic anhydride to give 2,3-dihydro-5-aryl-5H,6H-thiazolo[3,2-b]2,4-diazafluorene-3,6-diones (4), 2-methyl-2,3-dihydro-5-aryl-5H,6H-thiazolo[3,2-b]2,4-diazafluorene-3,6-diones (5) and 2,3-dihydro-6-aryl-6H,7H-thiazino[3,2-b]2,4-diazafluorene-4,7-diones (6), respectively.

2,3-Dihydro-2-arylmethylene-5-aryl-5H,6H-thiazolo[3,2-b]2,4-diazafluorene-3,6-diones (7) were prepared by the reaction of compounds (3) with chloroacetic acid and aromatic aldehydes in the presence of fused sodium acetate and acetic anhydride or by the reactions of (4) with aromatic aldehydes in the presence of acetic anhydride.

2-(Arylhydroazono)-5-aryl-2,3-dihydro-5H,6H-thiazolo[3,2-b]2,4-diazafluorene-3,6-diones (8) were synthesized by coupling (4) with aryldiazonium salts in the presence of pyridine.     

Quinazolines 1. Synthesis and chemical reactions of 6-chlorosulfonyl-quinazoline-2,4-diones

Treatment of quinazoline-2,4-dione and its symmetrical 1,3-dialkyl derivatives with chlorosulfonic acid gave the corresponding 6-chlorosulfonylquinazoline-2,4-diones. Reaction of the compounds obtained with nucleophilic agents (water, ammonia, aliphatic and cyclic amines) gave the corresponding free 2,4-dioxoquinazoline-6-sulfonic acids, 6-sulfamidoquinazoline-2,4-diones, and 2,4-dioxoquinazoline-6-sulfonic acid amides. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 420–427, March 2008.     

Oxidative ring opening of 3-hydroxyquinoline-2,4(1H,3H)-diones into N-(α-ketoacyl)anthranilic acids

N-(α-Ketoacyl)anthranilic acids were prepared by oxidative ring opening of 3-hydroxyquinoline-2,4(1H,3H)-diones by using paraperiodic acid (H₅IO₆) or sodium periodate (NaIO₄). The optimisation of the reaction conditions is described as well as the utilisation of N-(α-ketoacyl)anthranilic acids in the preparation of anthranilic acid hydrochlorides.     

Rearrangement of oxazolidinethiones to thiazolidinediones or thiazinanediones and their application for the synthesis of chiral allylic ureas and α-methyl-β-amino acids

A novel rearrangement has been found between oxazolidinethiones and acyl halides under N-acylation reaction conditions to afford N-substituted 2,4-thiazolidinediones and N-substituted 1,3-thiazinane-2,4-diones. These heterocycles were used for the synthesis of chiral allylic ureas and α-methyl-β-amino acids.     

Synthesis of Precursors of Heterocyclic cis-β-Amino Alcohols by Intramolecular Amidoalkylation of 4-Hydroxyoxazolidin-2-ones

The reaction of intramolecular amidoalkylation of 4-hydroxyoxazolidin-2-ones leads to formation of novel and rare heterocyclic systems: substituted 1,5,6,10b-tetrahydro[1,3]oxazolo[4,3-a]isoquinolin-3-ones, 3a,4,5,10b-tetrahydro[1,3]dioxolo[4',5':6,7]naphtho[1,2-d][1,3]oxazol-2(1H)-ones, and 5,6,10,10a-tetrahydro-1H-di[1,3]oxazolo[3,4-d:4,3-g][1,4]diazepine-3,8-diones. Mild reaction conditions and the simplicity of isolation of the compounds formed make it possible to obtain the indicated heterocycles in high yields.     

Quinazolines. 2*. unsymmetric 1,3-dialkyl-6-chlorosulfonyl- quinazoline-2,4-diones in nucleo- philic substitution reactions

The corresponding 6-chlorosulfonylquinazoline-2,4-diones were synthesized by the reactions of 1-methylquinazoline-2,4-dione and its 3-alkyl-substituted derivatives with chlorosulfonic acid. Treatment of the products with nucleophilic agents (water or ammonia, aliphatic and cyclic amines) gave 2,4-dioxoquinazolin-6-sulfonic acids or their amides.     

Microwave-assisted conversion of N-substituted oxazolidin-2,4-diones into α-hydroxyamides

N-Substituted oxazolidin-2,4-diones have been synthesized in a novel one-pot reaction by reacting cyanohydrins stepwise with 1,1′-carbonyldiimidazole and primary amines followed by acidic hydrolysis of the intermediate 4-imino-oxazolidin-2-ones. Their microwave-assisted conversion into α-hydroxyamides was accomplished by treatment with catalytic amounts of sodium methoxide in methanol.     

Enamines of 3-acyltetramic acids from β-enamino amides and amino acids

A novel approach for the synthesis of enamine derivatives of N-protected 3-acyltetramic acids is described. The synthetic procedure relies on α-C-acylation of β-enamino amides with N-protected α-amino acids and subsequent cyclisation of the obtained intermediates in refluxing TFA. The tetramic derivatives are obtained with very good enantiopurity (e.r. ≥95:5). Ring-enlarged analogues (piperidine-2,4-diones) can also be obtained from β-amino acids.     

Efficient construction of functionalized 5-carboxymethyl tetramic acids using N-Ac-l-aspartic anhydride as chiral building block

A novel method for the synthesis of densely functionalized optically active 5-carboxymethyl tetramic acids is reported. The proposed strategy is focused on the synthesis of 3,3′-disubstituted pyrrolidine-2,4-diones as useful molecules for the synthesis of natural products. The proposed methodology has been established by X-ray diffraction structure analysis.     

Solid-phase synthesis of 1,7-disubstituted-1,3,5-triazepane-2,4-diones

[reaction: see text]. The solid-phase synthesis of 1,7-disubstituted-1,3,5-triazepane-2,4-diones from resin-bound amino acids is described. The exhaustive reduction of solid-support bound amides with borane afforded the requisite secondary amines, which following treatment with phenyl isocyanatoformate and cleavage, provided the corresponding triazepane-2,4-diones.     

Unprecedented reactivity of 3-amino-1H,3H-quinoline-2,4-diones with urea: an efficient synthesis of 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones

Substituted 3-amino-1H,3H-quinoline-2,4-diones react with urea in acetic acid to give novel 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones in high yields. The same compounds were obtained, albeit with small yields, from 3-chloro-1H,3H-quinoline-2,4-diones and urea. In the proposed reaction mechanism, a molecular rearrangement of the primarily formed mono-substituted urea takes place. The prepared 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones were characterized by their ¹H, ¹³C, ¹⁵N NMR and IR spectra and atmospheric pressure chemical ionisation mass spectra.     

Direct synthesis of 3-(diaminomethylidene)chromane-2,4-diones from 3-formylchromones and hydroxylamine

3-(Diaminomethylidene)chromane-2,4-diones were synthesized from 4-oxo-4H-chromene-3-carbaldehyde and hydroxylamine in the presence of sodium hydroxide without isolation of intermediate products. Reflux of 3-(diaminomethylidene)chromane-2,4-dione in acetic anhydride gives rise to their monoacetyl derivatives at one of the amino groups.     

Reaction of 3-chloroquinoline-2,4-diones with ethanolamine and rearrangement of the reaction products

The reaction of tertiary α-chloroketones with ethanolamine has not been hitherto described in the literature. Herein, we describe the reaction of tertiary 3-chloroquinoline-2,4-diones with ethanolamine to give novel 3-(2-hydroxyethylamino)quinoline-2,4-diones. These compounds provide 3-(2-oxooxazolidin-3-yl)quinoline-2,4(1H,3H)-diones and new compounds with dimeric character after reaction with triphosgene. Molecular rearrangement proceeds during the reaction of 3-(2-hydroxyethylamino)quinoline-2,4-diones with isocyanic acid. Three types of reaction products arise: 2-(2-hydroxyethyl)imidazo[1,5-c]quinazoline-3,5-diones, 3-(2-hydroxyethyl)-3,3a-dihydro-2H-imidazo[4,5-]quinoline-4(5H)diones and primarily 5-hydroxy-1-(hydroxyethyl)-1′H-spiro[imidazolidine-5,3′-indole]-2,2′-diones. The reaction mechanism and product stereochemistry are discussed. The ¹H, ¹³C and ¹⁵N NMR spectra of the prepared compounds were measured, and all resonances were assigned from appropriate two-dimensional experiments.