Reaction of 2-perfluoroalkanoylcyclohexane-1,3-diones with diazomethane

Treatment of 2-perfluoroalkanoyl-5.5-dimethylcyclohexane-1,3-diones with a solution of diazomethane in diethyl ether led to the formation of the corresponding enol ethers and 3-hydroxy-6,6-dimethyl-3-perfluoroalkyl-2,3,6,7-tetrahydrobenzofuran-4(5H)-ones. The latter underwent dehydration on heating in boiling benzene in the presence of a catalytic amount of p-toluenesulfonic acid to give 6,6-dimethyl-3-perfluoroalkyl-6,7-dihydrobenzofuran-4(5H)-ones.     

Five-membered 2,3-dioxo heterocycles: LIV. Double spiro heterocyclization of methyl 1-aryl-3-benzoyl-4,5-dioxo-4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrrole-2-carboxylates with 3-arylamino-5,5-dimethylcyclohex-2-en-1-ones

Methyl 1-aryl-3-benzoyl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates reacted with 3-arylamino-5,5-dimethylcyclohex-2-en-1-ones in boiling benzene to give the corresponding 1,1′-diaryl-3′-benzoyl-4′-hydroxy-6,6-dimethyl-1,1′,2,4,5,5′,6,7-octahydrospiro[indole-3,2′-pyrrole]-2,4,5′-triones and 1′-aryl-4-arylamino-3-benzoyl-6′,6′-dimethyl-1′,2′,4′,5′,6′,7′-hexahydro-5H-spiro[furan-2,3′-indole]-2′,4′,5-triones whose structure was proved by X-ray analysis.     

Five-membered dioxo heterocycles: CIV. Reaction of methyl 1-aryl-3-benzoyl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates with cyclic enehydrazines. Crystal and molecular structure of N-[3′-benzoyl-1′-(4-chlorophenyl)-4′-hydroxy-6,6-dimethyl-2,4,5′-trioxo-1′,4,5,5′,6,7-hexahydrospiro-[indole-3,2′-pyrrol]-1(2H)-yl]benzamide

Methyl 1-aryl-3-benzoyl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates reacted with N′-(5,5-dimethyl-3-oxocyclohex-1-en-1-yl)benzohydrazides and N′-(5,5-dimethyl-3-oxocyclohex-1-en-1-yl)-2,2-diphenylacetohydrazide to give substituted N-[1′-aryl-3′-benzoyl-4′-hydroxy-6,6-dimethyl-2,4,5′-trioxo-1′,4,5,5′,6,7-hexahydrospiro[indole-3,2′-pyrrol]-1(2H)-yl]benz- and -diphenylacetamides.     

Five-membered 2,3-dioxo heterocycles: LX. Reaction of 3-aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with cyclic enehydrazino ketones. Crystalline and molecular structure of N-[3′-benzoyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6, 6-dimethyl-2,4,5′-trioxo-1′,4,5,5′,6,7-hexahydrospiro[indole-3,2′-pyrrol]-1(2H)-yl]-3-nitrobenzamide

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones react with N′-(5,5-dimethyl-3-oxocyclohex-1-en-1-yl)benzohydrazides to give the corresponding N-[3′-aroyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-2,4,5′-trioxo-1′,4,5,5′,6,7-hexahydrospiro[indole-3,2′-pyrrol]-1(2H)-yl]benzamides. The molecular and crystalline structure of one of the products, N-[3′-benzoyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-2,4,5′-trioxo-1′,4,5,5′,6,7-hexahydrospiro[indole-3,2′-pyrrol]-1(2H)-yl]-3-nitrobenzamide, was determined by X-ray analysis.     

Regioselective synthesis of polyfluoroalkyl-substituted 7-(1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-1-yl)-6,7-dihydro-1<Emphasis Type="Italic">H</Emphasis>-indazol-4(5<Emphasis Type="Italic">H</Emphasis>)-ones

3-Polyfluoroalkyl-6,6-dimethyl-7-(1H-1,2,3-triazol-1-yl)-6,7-dihydro-1H-indazol-4(5H)-ones were synthesized with high regioselectivity by 1,3-dipolar cycloaddition of terminal alkynes (phenylacetylene, hex- 1-yne, hept-1-yne, and but-3-yn-1-ol) to 7-azido-6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol-4(5H)-ones which were prepared by bromination of 6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol- 4(5H)-ones with N-bromosuccinimide in anhydrous carbon tetrachloride, followed by treatment of the corresponding 7-bromo derivatives with sodium azide.     

2-(Alkylamino)-3-aryl-6,7-dihydrobenzofuran-4(5H)-ones: Improved Synthesis and their Photophysical Properties

Furans are an important class of compounds and exhibit a diverse range of activities and properties. As such, improved synthetic access to furans is an important research goal. In the present report, a solvent- and catalyst-free reaction between 5,5-dimethyl-1,3-cyclohexanedione (dimedone), an aryl aldehyde and an isocyanide under microwave irradiation is presented. This method is significantly improved from previously described protocols in terms of applicability of wide ranging aryl aldehydes, better yields, shorter reaction times, facile work up and essentially no need of column chromatography. The photophysical properties of this series of compounds were studied for their possible applicability in the field of metal ion sensors. In solution, two compounds, 2-(cyclohexylamino)-3-(1H-indol-3-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-one (1 i) and 2-(tert-butylamino)-3-(1H-indol-3-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-one (1 j), underwent an observable color change from yellow to colorless in the presence of aluminum(III) ions. Further studies to investigate the UV absorption and luminescence behavior of these compounds revealed their utility as “naked-eye sensors” for aluminum detection.     

Five-membered 2,3-dioxo heterocycles: XCI. Reaction of 3-aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with dimedone. Crystalline and molecular structure of 3′-benzoyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-6,7-dihydrospiro[1-benzofuran-3,2′-pyrrole]-2,4,5′(1′H,5H)-trione

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with 5,5-dimethylcyclohexane-1,3-dione to give 3′-aroyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-6,7-dihydrospiro[1-benzofuran-3,2′-pyrrole]-2,4,5′(1′H,5H)-triones. The crystalline and molecular structures of 3′-benzoyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-6,7-dihydrospiro[1-benzofuran-3,2′-pyrrole]-2,4,5′(1′H,5H)-trione were determined by X-ray analysis.     

Chemical Transformations of 2-(3-Aryl-4-nitrobutanoyl)-5,5-dimethylcyclohexane-1,3-diones: II. Synthesis of New 6,7-Dihydro-1,2-benzoxazol-4(5<Emphasis Type="Italic">H</Emphasis>)-ones with Functionalized Side Chain

Transformation of the nitromethyl group in 3-(2-aryl-3-nitropropyl)-6,6-dimethyl-6,7-dihydro-1,2-benzoxazol-4(5H)-ones by the Nef reaction gave the corresponding aldehydes. Jones oxidation of the latter afforded carboxylic acids together with oxidative decarboxylation products. The possibility for the construction of heterocyclic fragment on the basis of the formyl or carboxylmethyl group of the resulting 6,7-dihydro-1,2-benzoxazol-4(5H)-one derivatives was studied.     

Application of N,3-diaryl-3-oxo-propanethioamide in synthesis: an efficient and mild domino approach to highly substituted fused chromenones

A convenient and rapid synthesis of hitherto unknown 3-aroyl-4-aryl-2-phenylamino-4H-benzo[g]chromene-5,10-diones in high yield from β-aroyl-thioacetanilide, aromatic aldehyde, and 2-hydroxy-1,4-naphthoquinone via InCl₃ catalyzed one-pot three-component tandem Knoevenagel condensation–Michael addition–intramolecular cyclization–elimination reaction sequence is disclosed for the first time. This domino protocol has been used to obtain highly substituted pyrano[3,2-c]chromen-5(4H)-ones and 7,7-dimethyl-7,8-dihydro-4H-chromen-5(6H)-ones from N,3-diaryl-3-oxo-propanethioamide, aromatic aldehyde, and 4-hydroxycoumarine or dimedone under mild reaction conditions. A plausible reaction mechanism is proposed. The 4H-pyrano[3,2-c]chromen-5-one and 7,7-dimethyl-7,8-dihydro-4H-chromen-5(6H)-one derivatives possessing 3-(2-chlorobenzoyl)-2-phenylamino-substituents further cyclized under basic conditions to yield penta-cyclic 7,13-diaryl-5,14-dioxa-13-aza-benzo[a]naphthacen-6,8(7H,13H)-dione and tetra-cyclic 6,12-diaryl-3,3-dimethyl-3,4-dihydro-2H-chromeno[2,3-b]quinolin-1,11(6H,12H)-dione, respectively.     

A study of the reactions of 2-aryl-4-hydroxy-6H-1,3-thiazin-6-ones with chromone-3-carboxaldehydes

Reaction of 3-formylchromones with 2-aryl-4-hydroxy-6H-1,3-thiazin-6-ones in the presence of pyridine leads to formation of a mixture of novel N-thioaroyl-5-hydroxy-2H,5H-pyrano[3,2-с]chromen-2-one-3-carboxamides and 2-aryl-5-(4′-oxochromen-3′-yl)-6,7-dihydro-4H,5H-pyrano[2,3-d][1,3]thiazine-4,7-diones. The yields of these compounds clearly depend on the nature of the substituent on the 3-formylchromone and on the reaction conditions.     

Synthesis of oxazole and furan derivatives via Rh2(OAc)4-catalyzed C≡X bond insertion of cyclic 2-diazo-1,3-diketones with nitriles and arylacetylenes

Abstract

A convenient and efficient procedure for the synthesis of 2-substituted-6,7-dihydrobenzo[d]oxazol-4(5H)-ones and 2-aryl-6,7-dihydrobenzofuran-4(5H)-ones through a Rh₂(OAc)₄-catalyzed C≡X (X?=?N, C) insertion of cyclic 2-diazo-1,3-diketones with nitriles and aromatic alkynes has been developed. This reaction uses readily available starting materials and stable cyclic 2-diazo-1,3-diketone compounds, with desired products formed in good to high yields. A tentative mechanism involving a C≡X bond insertion and 1,5-dipolar electrocyclization/ring opening and cyclization sequence for this reaction is proposed.     

Synthesis of 6H,8H-isoquino[2,3-c][1,3]benzothiazin-8-ones

6H,8H-Isoquino-1,3-benzothiazin-8-ones have been prepared by reaction of 6,7-dimethoxy-2H-1,3-benzo-thiazines with homophthalic anhydride and by photocyclization of 3-benzoyl-4-methylene-6,7-dimethoxy 2H-1,3-benzothiazine. The compounds are thia analogues of protoberberine alkaloids containing a sulfur atom at C-5 and a lactam function at C-8. The mass spectra of the title compounds are discussed.     

Five-membered 2,3-dioxo heterocycles: LI. Reaction of 3-aroyl-2,4-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with 3-amino-5,5-dimethylcyclohex-2-en-1-ones

3-Aroyl-2,4-dihydro-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones react with N-unsubstituted and N-substituted 3-amino-5,5-dimethylcyclohex-2-en-1-ones to give 3′-aroyl-4′-hydroxy-1′-(o-hydroxy-phenyl)-6,6-dimethyl-6,7-dihydrospiro[indole-3,2′-pyrrole]-2,4,5′(1H,1′H,5H)-triones. The molecular and crystalline structure of the 1-cyclohexyl-substituted derivative was studied by X-ray analysis.     

Synthesis of benzimidazolone derivatives based on 2-acylcyclohexane-1,3-diones alkoximes

2-(1-Alkoxyiminoalkyl)cyclohexane-1,3-diones undergo at heating Beckmann rearrangement to give 6,7-dihydro-1,3-benzoxazol-4(5H)-one derivatives that under treatment with amines in acid medium are converted into 1,5,6,7-tetrahydro-4H-benzimidazol-4-ones. In reaction of 6,7-dihydro-1,3-benzoxazol-4(5H)-ones with O-ethylhydroxylamine 4-ethoxyimino derivatives were obtained that treated with hydrochloric acid formed the corresponding N-ethoxybenzimidazolones.     

CAN-promoted, diastereoselective synthesis of fused 2,3-dihydrofurans and their transformation into tetrahydroindoles

The reaction between 1,3-cyclohexanediones and chalcones (or their vinilogs) in the presence of 2.5 equiv of cerium(IV) ammonium nitrate afforded trans-2-arylcarbonyl-3-aryl (or styryl)-2,3,6,7-tetrahydrobenzofuran-4(5H)-ones in good to excellent yields and in high diastereoselectivities. The method was also extended to the preparation of derivatives of the 5,6-dihydro-2H-cyclopenta[b]furan-4(3H)-one system. The fused 2,3-dihydrofuran derivatives were transformed into 1-alkyl-2-acyl-3-aryl-6,7-dihydroindole-4(5H)-ones by 2,3-dehydrogenation followed by reaction with primary amines. The direct reaction of the tetrahydrobenzofuran-4(5H)-one compounds derived from dimedone with amines gave 1-alkyl-2-alkylimino-3-aryl-6,7-dihydroindole-4(5H)-ones, while starting materials derived from 1,3-cyclohexanedione underwent an unprecedented 2-deacylation reaction and gave 1-alkyl-3-aryl-6,7-dihydroindole-4(5H)-ones.     

Nucleophilic trifluoromethylation of RF-containing 4-quinolones, 8-aza- and 1-thiochromones with (trifluoromethyl)trimethylsilane

Reactions of N-substituted 2-polyfluoroalkyl-4-quinolones and 8-aza-5,7-dimethyl-2-polyfluoroalkylchromones with (trifluoromethyl)trimethylsilane proceed mainly as a 1,4-nucleophilic trifluoromethylation to give N-substituted 2,2-bis(polyfluoroalkyl)-2,3-dihydroquinolin-4(1H)-ones and 5,7-dimethyl-2,2-bis(polyfluoroalkyl)-2,3-dihydro-4H-pyrano[2,3-b]pyridin-4-ones after acid hydrolysis. Similar reaction with 2-trifluoromethyl-4H-thiochromen-4-one proceeds as a 1,2-addition to give 2,4-bis(trifluoromethyl)-4H-thiochromen-4-yl trimethylsilyl ether.     

Reactions of 1,1-diaryl-2-isopropylidene-3-methylenecyclopropanes with C,N-diarylnitrones and nitrile oxides

The reactions of unactivated bis(methylene)cyclopropanes with nitrones and nitrile oxides have been investigated. The 1,1-diaryl-2-isopropylidene-3-methylenecyclopropanes react with the C,N-diarylnitrones to give a mixture of 2,2-dimethyl-1,6-diaryl-3-(diarylmethylene)piperidin-4-ones and 5-methyl-1-aryl-1-(arylamino)-4-(diarylmethylene)hex-5-en-3-ones. 2,3-Dihydro-3-methylenepyridin-4(1H)-ones are obtained by reaction of 1,1-diaryl-2-isopropylidene-3-methylenecyclopropanes with nitrile oxides.     

Heterocyclizations of 5-methylpyrazol-3-amine with unsaturated arylaliphatic carboxylic acid derivatives

Cyclocondensation of 5-methylpyrazol-3-amine with methyl cinnamate and arylmethylidenemalonic acids in DMF and methanol leads to the formation of 7-aryl-2-methyl-6,7-dihydropyrazolo[1,5-a]-pyrimidin-5(4H)-ones. Arylmethylidenemalonic acids react with the title amine at a ratio of 1:2 in nitrobenzene to give 4-aryl-3,5-dimethyl-1,7-dihydrodipyrazolo[3,4-b:4′,3′-e]pyridines. Heterocyclizations of 5-methylpyrazol-3-amine with 5-arylmethylidene-2,2-dimethyl-1,3-dioxane-4,6-diones or their precursors, para-substituted benzaldehydes and 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum’s acid) in all solvents (methanol, DMF, and nitrobenzene) give the corresponding 4-aryl-3-methyl-2,4,5,7-tetrahydropyrazolo[3,4-b]pyridin-6-ones. The structure of 3-methyl-4-(4-nitrophenyl)-2,4,5,7-tetrahydropyrazolo[3,4-b]pyridin-6-one was proved by X-ray analysis.     

Five-membered 2.3-dioxo heterocycles: LXVIII. Three pathways in the reaction of methyl 3-aroyl-1-aryl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates with 3-amino-5,5-dimethylcyclohex-2-en-1-one

Methyl 3-aroyl-1-aryl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates reacted with 3-amino-5,5-dimethylcyclohex-2-en-1-one having no substituent on the nitrogen atom to give 3-aroyl-4-arylamino-6′,6′-dimethyl-6′,7′-dihydro-5H-spiro[furan-2,3′-indole]-2′,4′,5′(1′H,5′H)-triones or methyl 12-aroyl-11-aryl-9-hydroxy-5,5-dimethyl-3,10-dioxo-8,11-diazatricyclo[7.2.1.0^2,7]dodec-2(7)-ene-1-carboxylates. The latter underwent thermal recyclization to 3′-aroyl-1′-aryl-4′-hydroxy-6,6-dimethyl-6,7-dihydrospiro[indole-3,2′-pyrrole]-2,4,5′(1H,1′H,5H)-triones.     

Highly regioselective direct halogenation: a simple and efficient method for preparing 4-halomethyl-5-methyl-2-aryl-1,3-thiazoles

An unprecedented C4-methyl regioselective halogenation of 4,5-dimethyl-2-aryl-1,3-thiazoles (1) has been accomplished. The reaction of compound 1 with N-chlorosuccinimide and N-bromosuccinimide under mild conditions provides an efficient and operationally simple method for obtaining 4-chloromethyl-5-methyl-2-aryl-1,3-thiazoles (2) and 4-bromomethyl-5-methyl-2-aryl-1,3-thiazoles (3), respectively, in good yields without the formation of 4-methyl-5-halomethyl regioisomers.