Unsaturated Diketones Research Articles

Plant anthraquinones: Classification, distribution, biosynthesis, and regulation.

Anthraquinones are polycyclic compounds with an unsaturated diketone structure (quinoid moiety). As important secondary metabolites of plants, anthraquinones play an important role in the response of many biological processes and environmental factors. Anthraquinones are common in the human diet and have a variety of biological activities including anticancer, antibacterial, and antioxidant activities that reduce disease risk. The biological activity of anthraquinones depends on the substitution pattern of their hydroxyl groups on the anthraquinone ring structure. However, there is still a lack of systematic summary on the distribution, classification, and biosynthesis of plant anthraquinones. Therefore, this paper systematically reviews the research progress of the distribution, classification, biosynthesis, and regulation of plant anthraquinones. Additionally, we discuss future opportunities in anthraquinone research, including biotechnology, therapeutic products, and dietary anthraquinones.

Schiff bases of 1,5-diarylpent-4-ene-1,3-diones and their metal complexes: Synthesis, characterization and fluorescent studies

Four Schiff bases (H2L1 to H2L4) were synthesized by the condensation of o-aminophenol and unsaturated diketones (1,5-diarylpent-4-ene-1,3- -diones). Analytical, IR, 1H-NMR and mass spectral data revealed their existence in the imine?enamine form. Dibasic tetradentate coordination of the Schiff bases in their ML complexes (M = Cu(II), Ni(II), Co(II), Zn(II), Cd(II), and Hg(II)) was established based on physical, analytical and spectral data. The fluorescent studies of H2L4 showed that the fluorescence emission maxima shifted with increasing polarity and hydrogen bonding ability of the solvent. Paramagnetic Cu(II), Ni(II) and Co(II) ions decrease the fluorescence intensity with increasing concentration of the metal ion while diamagnetic Zn(II), Cd(II) and Hg(II) ions have very little influence on the fluorescence intensity of the Schiff base H2L4.

Synthesis, characterization, and fluorescence study of phthalhydrazidylazo derivative of an unsaturated diketone and its metal complexes

The coupling of diazotized luminol with the unsaturated diketone 1,7-diphenylhepta-4,6-diene-1,3-dione yielded a new type of tridentate ligand (H2L). Analytical, IR, 1 H NMR, and mass spectral data indicate the existence of the compound in the intramolecularly hydrogen-bonded keto-hydrazone tautomeric form. Dibasic tridentate coordination of the compound in its (ML(H2O)) complexes (M = Cu(II), Ni(II) and Zn(II)) was established on the basis of analytical and spectral data. The Ni(II) and Zn(II) chelates are diamagnetic while Cu(II) complex showed normal paramagnetic moment. The uorescence maxima of the compound in dierent solvents show that the emission wavelength increases with increases in the polarity of the solvent. The uorescence intensity in the presence of Cu(II) ion shows a gradual

Roger Bishop's Research Leadership in Crystal Engineering and Supramolecular Chemistry

On 21November 2011,many colleagues, students and friends of Emeritus Professor Roger Bishop gathered in the School of Chemistry at the University of New South Wales (UNSW) to celebrate his research and mark his retirement. Roger was honoured with a symposium in crystal engineering, including presentations by Jagadese Vittal (National University of Singapore), Keiichiro Ogawa (University of Tokyo), Mark Spackman (University of Western Australia), Stuart Batten (Monash University), Chris Easton (Australian National University), Kate Jollife (University of Sydney), Chris Richardson (University of Wollongong), Alison Ung (University of Technology, Sydney), Qinghong Lin (iNova Pharmaceuticals) and Ian Dance (UNSW). J. J. Vittal reported some recent work on solid state photoreactions, which, significantly, connected with the research of Gerhard Schmidt (Weizmann Institute) who, in systematising organic solid state photochemistry as it was known in 1971, originated the name and concept of crystal engineering [Pure Appl. Chem. 1971, 27, 647–678]. It is interesting that Roger Bishop, as a doctoral student at Cambridge University, was also publishing at this time (1969–1972) on photochemical reactions of unsaturated diketones. Roger arrived at UNSW in 1974, and was provided with ready opportunities for X-ray diffraction determination of crystal structures and examination of crystal packing, and so it is not surprising that he was soon contributing to the nascent field of crystal engineering. His early work was with symmetrical bicyclic diols, which formed high symmetry porous lattices constructed with hydrogen bonds, and are capable of being engineered to include various small molecules. Much of Roger’s early research at UNSW explored this theme of host lattices based on designed hydrogen bonds, but his purview soon expanded to all types of intermolecular interactions. He was strongly involved in the early development of supramolecular chemistry, particularly the branch of supramolecular chemistry that does not depend on metal complexation. In this Research Front, Roger Bishop provides a detailed review of host-guest systems (clathrates) and inclusion phenomena that are stabilised by intermolecular interactions weaker than conventional hydrogen bonds. Here, crystal engineering is more difficult than when strong hydrogen bonds and metal ligation are the connecting elements. But, with characteristic insight and precision, Roger reveals some key characteristics of successful crystal engineering of host molecules, including C2 symmetry, V-shape, potential for aryl–aryl intermolecular interactions, and potential for halogen intermolecular bonding, including halogen–p intermolecular bonding. Roger designed and investigated 19 potential host molecules, 18 of which functioned as the expected inclusion hosts. A 95% success rate is still rare in contemporary crystal engineering. The journal CrystEngComm profiles Roger Bishop as a prominent author in the field, and includes Fig. 1 exemplifying design features for which he is well known. The Roger Bishop Crystal Engineering Symposium in 2011 embraced these themes and some further dimensions of Roger’s research influences. Mark Spackmann discussed the classic lattices formed by hydroquinone and by Dianin’s unsymmetrical compound, related to Roger’s original diol lattices. Stuart Batten described amazing multifunctional supramolecular nanoballs, Chris Easton played molecular engineer with selfassembling cyclodextrin rotaxanes, Kate Jolliffe engineered peptides for molecular recognition, and Chris Richardson described his metal-organic frameworks. The subtleties of the organic solid state were evident in Keiichiro Ogawa’s presentation on molecular torsions, while Qinghong Lin (a Bishop student) covered the commercial dimension of polymorphism in pharmaceuticals. Alison Ung (an early Bishop student), in describing some synthetic work using the Ritter reaction, reminded us that Roger is skilled in organic synthesis and research mentoring. Roger has published many papers on Ritter-type reactions, and was awarded the Olle Prize of the Royal Australian Chemical Institute (1993) for one of these publications. Roger Bishop is a regular participant in the International Conferences on the Chemistry of the Organic Solid State. He organised the sixteenth such meeting, in Sydney in July 2003,

Reaction of alicyclic reformatsky reagents with 2-arylmethylene-1,3-diphenylpropane-1,3-diones

Previously we found that the reaction of alicyclic Reformatsky reagents with 1,3-diarylprop-2-ene-1ones resulted in the substituted spirodihydropyranones [1, 2]. In continuation of these studies we examined the reaction of the Reformatsky reagents IIa and IIb derived from methyl 1-bromocycloalkylcarboxylates Ia and Ib and zinc with 2-arylmethylene-1,3-diphenylpropane-1,3-dione IIIa–IIIf. Our study showed that addition of the organozinc reagents IIa–IIb to the unsaturated diketones IIIa–IIIf occurs in 1,4-position to form the intermediates IVa–IVe, Va–Vf followed by the cyclization with the release of bromozinc methylate to form 10-aryl-9-benzoyl-8-phenyl-7-oxaspiro[4.5]dec-8-ene-6-ones VIa–VIf and 5-aryl-4benzoyl-3-phenyl-2-oxaspiro[5.5]undec-3-ene-1-ones VIIa–VIIf, respectively. DOI: 10.1134/S1070363211060302

β-Diketones bearing electron-donating chromophores and a novel β-triketone: synthesis and reversible fluorescence behavior

Saturated and unsaturated β-diketones bearing 4- N, N-dimethylaminophenyl substituent and a novel β-triketone were synthesized. These β-diketones exist in both cis-enol and keto forms in solution, and their relative contents were determined by 1H NMR measurements. In contrast, for the β-triketone, only enol form was observed in a solution. A strong fluorescence quenching was observed for unsaturated diketones as compared with the saturated ones. These β-diketones displayed reversible photoinduced ketonization as revealed by UV–vis spectroscopy. The fluorescence emission of the saturated β-diketones faded gradually during UV irradiation. The fluorescence emission of these saturated β-diketones can thus be reversibly switched between the enol form ‘ON’ and the keto form ‘OFF’ based on keto-enol tautomerization.

Remarkable phosphine-effect on the intramolecular aldol reactions of unsaturated 1,5-diketones: highly regioselective synthesis of cross-conjugated dienones.

We report a phosphine-mediated intramolecular aldol cyclization of unsaturated diketones that proceeds with extremely high levels of regioselectivity for the cross-conjugated bicyclic dienone products. The sense of regioselectivity observed in this reaction is complementary to that obtained using traditional aldol conditions. Experimental evidence that supports the involvement of a phosphine Michael adduct is described.

An approach to the synthesis of phomactins using a Wittig rearrangement

Preliminary studies to evaluate the feasability of an approach to the synthesis of the phomactin diterpenes are outlined. The key step is the 2,3-Wittig rearrangement of the propargylic ether 32 which gives a mixture of the diastereoisomeric alcohols 33. Oxidation to the ketones 34 and 35 followed by conjugate addition of lithium dimethylcuprate and deprotection gives the unsaturated diketone 37 so providing a strategy for the synthesis of the cyclohexenyl core of the phomactins.

ChemInform Abstract: Levulinic acid in Organic Synthesis

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Heterocyclization reaction of propargyl acetate with β-dicarbonyl compounds

The regiochemistry of the reaction of propargyl acetate with CH acids in the presence of mercury(II) acetate in dimethylsulfoxide has been investigated. Derivatives of furan or unsaturated diketones were isolated depending on the nature of the 1,3-dicarbonyl and the possibility of reduction of the organomercury intermediate.

Konformation und Bromierung von Bicyclo[3.3.1]nonan‐2,6‐dion sowie Dehydrobromierung der Bromketone. – Verbesserte Synthese von Bicyclo[3.3.1]nona‐3,7‐dien‐2,6‐dion

Conformation and Bromination of Bicyclo[3.3.1]nonane‐2,6‐dione and Dehydrobromination of the Bromo Ketones. – Improved Synthesis of Bicyclo[3.3.1]nona‐3,7‐diene‐2,6‐dioneBromination by copper(II) bromide of bicyclo[3.3.1]nonane‐2,6‐dione (1) affords the epimeric α‐bromo diketones exo‐and endo‐5 and, eventually, the α, α′‐dibromo diketones exo‐ and endo‐7 (3:7) in high yield. Dehydrobromination of the mixtures of bromo diketones by calcium carbonate in dimethylacetamide yields the unsaturated diketones 6 (30%) and 2 (72%), respectively. Bromination of 1 by molecular bromine is less selective and furnishes mixtures of brominated diketones consisting of exo‐ and endo‐7, 8 and the tetrabromo diketone 10. An excess of bromine yields pure 10. – The ethylene acetal 12 is brominated by pyridinium perbromide to produce the α,α′‐dibromo acetal 13 which is very reluctant towards 1,2‐dehydrobromination by potassium tert‐butoxide. Thus, with an excess of potassium tert‐butoxide in tetrahydrofuran, 1,2‐dehydrobromination is achieved only on one side to afford 14. In contrast, potassium tert‐butoxide in dimethyl sulphoxide induces a transannular dehydrobromination leading to the diacetal 15 of 3‐bromonoradamantane‐2,6‐dione. – The conformations of 1,10, and 13 in the solid state are determined by X‐ray diffraction analyses. From torsional angles, vicinal proton coupling constants are calculated with the aid of the Karplus equation and compared to those determined from solutions by high‐field NMR spectroscopy. The reasonable agreement provides the basis for the assessment of the configuration and conformation for exo‐ and endo‐7. magnified image

Adsorption and deuteration of acetone- d6 on Pt/ZnO catalysts: An IR study of the effects of sample pretreatment

We report the adsorption and the deuteration of acetone- d 6 on differently pretreated Pt/ZnO catalysts, studied by FTIR. On mildly reduced samples the deuteroacetone is mainly adsorbed at room temperature (RT) in molecular end-on forms; upon heating at 373 K minor amounts of CO are formed. These findings indicate that the adsorption on the mildly reduced sample at RT is only molecular, while abstraction of deuterium atoms and breaking of CC bonds occurs upon heating. The interaction of strongly reduced samples with acetone- d 6 at RT causes an almost complete loss of IR transmission and the growth of strong bands in the OD stretching region; this behaviour indicates that on this sample the deuteroacetone very easily loses D atoms. Moreover, a quite broad band at 1580 cm −1 emerges after a long contact time, related to the formation of an unsaturated diketone species. The deuteration reaction on the mildly reduced samples produces, at RT, bands assigned to modes of perdeuteroisopropylalcohol; however, large amounts of unreacted deuteroacetone remain in the cell, even after many hours of contact. The reaction with D 2 on strongly reduced samples also in this case produces perdeuteroisopropylalcohol. The deuteroacetone present in the cell or chemisorbed on the surface, however, is almost completely depleted. The data indicate a higher dehydrogenating and hydrogenating activity of the strongly reduced samples in comparison with the mildly reduced ones, mainly due to changes in the surface composition of the metallic particles.

ChemInform Abstract: The Complex Reaction of Acetohydrazides with Unsaturated Diketones: Alternative Cyclizations to 1,2‐Diazepin‐3‐ones and Pyrazolo(3,4‐b)pyridines.

AbstractThe reaction of the cyanoacetohydrazide (I) with the unsaturated diketones (II) leads either to the 1,2‐diazepinones (III) together with the acetohydrazones (IV) or to the pyrazolo(3,4‐b)pyridines (V).

The complex reaction of acetohydrazides with unsaturated diketones: Alternative cyclizations to 1,2‐diazepin‐3‐ones and pyrazolo[3,4‐b]pyridines

AbstractThe reaction of 2‐cyanoacetohydrazide (1) and 2‐(ethoxycarbonyl)acetohydrazide (26) with unsaturated 1,3‐diketones leading with moderate yields to 1,2‐diazepinones (3, 23, 24) and pyrazolo[3,4‐b]pyridines (5, 15, 20, 25) together with the corresponding acetohydrazones have been studied. The reaction course depends on the temperature and the relative reactivity of the carbonyl groups of the starting materials. When one of these carbonyl groups is less reactive (benzoyl or ethoxycarbonyl groups), the reaction does not yield diazepinones but only pyrazolo[3,4‐b]pyridines and/or acetohydrazones.

ChemInform Abstract: Use of β‐Sulfonylvinyl Ketones as Equivalents to Vinyl Ketones in Robinson Anellation. Convergent, Highly Stereoselective Preparation of a Hydrindanol Related to Vitamin D from 2‐Methylcyclopent‐2‐enone and Lithiated E‐But‐2‐enyldiphenylphosphine Oxide.

AbstractConjugate addition of lithiated butenyldiphenylphosphine oxide to the cyclopentenone (III) yields the intermediate enolate (IV) which reacts with the β‐sulfonylvinyl ketones (V) to form the unsaturated diketones (VI).

ChemInform Abstract: Preparation of Hydrindenones from 2‐Methylcyclopent‐2‐enone and the Carbanion of (E)‐But‐2‐enyldiphenylphosphine Oxide: Efficient Enolate Trapping with β‐Sulphonylvinyl Ketones.

AbstractThe sulphonylvinyl ketones (II) are transformed into the unsaturated diketones (V) which are hydrogenated and cyclized to give the hydrindenones (VII).

Synthesis and hydroboration/oxidation of tricyclo(5.2.1.0 4,10)dec-8-ene-2,5-dione(bis-acetal): new synthetic entry to tricyclo(5.2.1.0 4,10)decane-2, 5, 8-trione

Tricyclo(5.2.1.0 4,10)decane-2,5,8-trione (4) has been synthesized from the corresponding bis-acetal of the unsaturated diketone 20 by a hydroboration/oxidation/deprotection sequence.

The chemistry of thujone. IX. Thujone as a chiral synthon for the synthesis of optically active steroid analogues. The vinylpicoline route

AbstractThe thujone‐derived enone 1, upon base‐catalyzed reaction with 2‐methyl‐6‐vinylpyridine is converted to the pyridine analogue 5 (Scheme 1). Catalytic reduction of the latter to 6 generates two new centers of chirality which eventually become C(8) and C(14) in the ultimate synthetic steroid analogue 12. An X‐ray analysis of 6 establishes the structure and absolute configuration so as to determine its suitability in subsequent synthetic studies. The acetal derivative 7, via Birch reduction, hydrolysis, and internal aldol cyclization, is converted into the cyclohexenone analogue 10 (Scheme 2). This ‘one‐pot’ process affords an efficient conversion of the pyridine ring into a cyclohexenone system required for A‐ring construction of the steroid skeleton. Finally, conversion of 10, via the unsaturated diketone 11, provides the chiral steroid analogue 12.

Synthesis and Photochemical Behaviour of 2‐Amino‐1,3‐Cyclohexadienes

AbstractThe reaction of the 4,4‐dialkylated 2‐cyclohexenones 1 or 2 with a twofold excess of a secondary amine 3 affords the 2‐amino‐1,3‐cyclohexadienes 4 and 5, respectively. Irradiation (λ ≧ 300 nm) of the morpholino derivative 4a yields a mixture of the isomeric 3‐morpholino‐6‐methyl‐1,3,5‐heptatrienes 6 and 7, while 5 gives only one corresponding product 8. The reaction of enone 1 with an equimolar amount of pyrrolidine (3c) affords the bis‐enamine 9 which is converted to the unsaturated diketone 10 by oxidative hydrolysis.

Hydrogenolytic opening of 4,4-dimethyl-4a,5-epoxy-a-homocholestane derivatives and mass spectra of some reaction products

The hydrogenolytic opening of the epoxide ring of all four stereoisomeric 3-acetoxy-4,4-dimethyl-4a,5-epoxy-A-homocholestanes was investigated. The reaction proceeds at the more substituted carbon atom C(5), giving rise to 4a-hydroxy-5,6-unsaturated derivatives. The hydrogenation of the 5,6-double bond of these allylic alcohols affords 4,4-dimethyl-A-homo-5β-cholestane derivatives. The mass spectra of 3,4a-diketones XI and XVII and 4a-ketones XVI and XXVIII to XXX were also studied. In the case of the saturated diketone XVII it was observed that the most abundant metastable peak corresponds to a two-step fragmentation process. The decomposition of the molecular ion of the unsaturated diketone XI is associated with ring A expansion. The mass spectra of 3-acetoxy ketones XVI and XXVIII are characterized by an elimination of a C4H8 molecule from the contracted ring A of the ion [M-CH3COOH]+. The unexpected elimination of the species C6H11, C6H12, and C6H13 from the ring A of the molecular ions of 3-hydroxy ketones XXIX and XXX is shown to be preceded by hydroxyl migration and ring A rearrangement.