ABSTRACT
Thermal decomposition of the phenyliodonium ylide of lawsone gives rise to a highly reactive cyclic α,α'-dioxoketene, indanedioneketene, which reacts with electron-rich dienophiles such as enol ethers to afford [4 + 2] cycloadducts. The initially formed 2,3-dihydro-2-alkoxy-indeno[1,2-b]pyrano-4,5-diones are labile compounds since through an opening of the pyranone ring upon heating they easily tautomerize to alkoxyallylidene-indenedione derivatives and under acid-catalysis they are additionally transformed to 2-(1,3-dihydroxyallylidene)-1H-indene-1,3(2H)-dione or by loss of alcohol to indeno[1,2-b]pyran-4,5-diones. A DFT study explains the polar nature of the cycloaddition reaction, the observed reactivity and suggests a possible mechanism operating in these reactions.
ABSTRACT
Indanedioneketene, a compound resulting from the thermal degradation of the phenyliodonium ylide of lawsone, dimerizes quantitatively to a spiro-oxetanone derivative, a key compound for further transformations. A theoretical electronic structure study of this unusual for alpha-oxoketenes [2 + 2] cyclization reaction both in the gas phase (DFT, MP2) and in dichloromethane solution (DFT), provides support for (a) a single-step, transition-state (involving a four-membered cyclic ring) charge-controlled, concerted mechanism and (b) a [4 + 2] cyclization reaction, not observed but studied theoretically in this study. A parallel study of an open-chain alpha,alpha'-dioxoketene dimerization explains the difference in the stability and reactivity observed experimentally between the cyclic and open-chain products.
Subject(s)
Computer Simulation , Indans/chemistry , Ketones/chemistry , Lactones/chemical synthesis , Spiro Compounds/chemical synthesis , Cyclization , Dimerization , Lactones/chemistry , Molecular Structure , Spiro Compounds/chemistryABSTRACT
Indenocarboxamides, resulting from the sequential addition of two arylamine equivalents to indanedione ketene dimer, are oxidized by [bis(trifluoroacetoxy)iodobenzene] to fused indeno-1,4-diazepinones in yields depending on the substituents on both aromatic rings. A plausible reaction pathway explaining the formation of the title compounds, as well as the formation of the two other minor products of the reaction, through a common intermediate, is suggested.
Subject(s)
Azepines/chemistry , Indenes/chemistry , Iodobenzenes/chemistry , Amides/chemical synthesis , Amides/chemistry , Amines/chemistry , Cyclization , Molecular Structure , Oxidation-Reduction , StereoisomerismABSTRACT
Although 1,3-dioxoindane-2-carboxylic acid is highly unstable, its enamino derivatives can be isolated by careful hydrolysis of their esters with 2,4-dihydroxy-1,4-naphthoquinone. Crystal structure determination reveals the formation of two intramolecular hydrogen bonds, offering thus a possible explanation for the stability of these acids.
Subject(s)
Amines/chemistry , Carboxylic Acids/chemistry , Indans/chemistry , Crystallography, X-Ray , Hydrogen Bonding , Molecular StructureSubject(s)
Antineoplastic Agents/pharmacology , Cell Membrane Permeability/drug effects , Cell Proliferation/drug effects , Indenes/pharmacology , Protein Kinase Inhibitors/pharmacology , Pyrimidines/pharmacology , Receptor Protein-Tyrosine Kinases/antagonists & inhibitors , Umbilical Cord/drug effects , Adenosine Triphosphate/metabolism , Antineoplastic Agents/chemical synthesis , Cell Membrane Permeability/physiology , Cells, Cultured , Humans , Inhibitory Concentration 50 , Protein Kinase Inhibitors/chemical synthesis , Spectrum Analysis , Umbilical Cord/cytology , Umbilical Cord/metabolismABSTRACT
The highly reactive indanedioneketene 5, resulting from the thermal decomposition of phenyliodonium ylide of 2-hydroxy-1,4-naphthoquinone (lawsone, 4), in the absence of nucleophiles dimerizes to the corresponding tetraoxo spiro oxetanone 6 in quantitative yield. This oxetanone exhibits an interesting reactivity toward amines.
Subject(s)
Amines/chemistry , Indans/chemistry , Ketones/chemistry , Crystallography, X-Ray , Dimerization , Hydrogen Bonding , Models, Molecular , Molecular Structure , Naphthoquinones/chemical synthesis , Naphthoquinones/chemistry , Stereoisomerism , TemperatureABSTRACT
A DFT study on the intramolecular thermal phenyl migration in iodonium ylides supports a concerted mechanism. In contrast to the two, different than each other, suggested mechanisms, involving only intermediates, this study indicates a single-step, transition-state one--involving a five-membered cyclic ring--with no intermediates. The frontier-orbital-controlled migration also confirms the different thermal behavior of two different ylides.
ABSTRACT
[reaction: see text] Thermal decomposition of phenyliodonium ylide of 2-hydroxy-1,4-naphthoquinone (lawsone) in the presence of indole derivatives affords 3-acylated indoles existing in their enol forms, through a ring contraction and alpha,alpha'-dioxoketene formation reaction. The same reactants afford 3-(3-indolyl)-2-hydroxy-1,4-naphthoquinones in a copper-catalyzed reaction. Enamines, among other C-nucleophiles tested, give analogous results.
Subject(s)
Indoles/chemistry , Naphthoquinones/chemistry , Onium Compounds/chemistry , Molecular Structure , Onium Compounds/chemical synthesisABSTRACT
The phenyliodonium ylide of 2-hydroxy-1,4-naphthoquinone reacts with aminoesters, ureas, aminoalcohols and aminophenols in refluxing dichloromethane to afford good yields of indanedione 2-carboxamido compounds, that in solution exist in an enol-amide form. The same reactants in a copper-catalyzed reaction afford mainly the corresponding N-arylo compounds. Arylhydrazines are mainly oxidized by the ylide and arylation occurs only in a low yield.
Subject(s)
Amines/chemistry , Heterocyclic Compounds/chemical synthesis , Naphthoquinones/chemistry , Onium Compounds/chemistry , Catalysis , Models, BiologicalABSTRACT
Aryliodonium ylides of 2-hydroxy-1,4-naphthoquinone react with amines in refluxing dichloromethane to afford good yields of indanedione 2-carboxamides 5, through a ring-contraction and alpha,alpha'-dioxoketene formation reaction. These amides exist in solution in an unusual enol-amide form. In contrast, the same reactants in a copper-catalyzed reaction afford arylamines and 3-iodo-4-hydroxy-1,2-naphthoquinone.
ABSTRACT
Three triptycene quinones bearing methoxy groups were prepared following a Diels-Alder methodology and were evaluated for antioxidant and anti-inflammatory activity bearing in mind their structural features that could justify intervention with free radical processes. Improved synthetic pathways were achieved for target molecules 9,10-dihydro-5,8-dimethoxy-9,10-[o]benzenoanthracene-1,4-dione (4), 9,10-dihydro-2-hydroxy-5,8-dimethoxy-9,10-[o]benzenoanthracene-1,4-dione (6), and 9,10-dihydro-2,5,8-trimethoxy-9,10-[o]benzenoanthracene-1,4-dione (9). Under our experimental conditions these compounds showed very significant antioxidant activity offering protection against lipid peroxidation of rat hepatic microsomal fraction while inhibiting the reaction completely at very low concentrations (12.5-80 microM). Moreover, compound 6 that was examined, inhibited by 44% (at 120 microM) lipoxygenase acitvity while the anti-inflammatory activity of the compounds, as assessed by the reduction of the mouse paw edema induced by Freund's complete adjuvant, was significant and comparable to that of indomethacin.
Subject(s)
Anti-Inflammatory Agents/chemical synthesis , Anti-Inflammatory Agents/pharmacology , Antioxidants/chemical synthesis , Antioxidants/pharmacology , Free Radicals/metabolism , Quinones/chemical synthesis , Quinones/pharmacology , Animals , Mice , Rats , Structure-Activity RelationshipABSTRACT
Triptycenene quinone 1 was converted to triptycene cyclopentenedione 5 through hydroxyquinone-phenyliodonium ylide formation and thermal ring contraction of the latter. Cyclopentenedione 5 reacts as a dienophile and as a dipolarophile with dienes and nitrile oxides, affording polycyclic adducts bearing the triptycene moiety.
