The heavy atom effect on photocleavage of DNA by mono-hydroxyl halogenated corroles

<正>DNA photocleavage properties of halogenated mono-hydroxyl corrole 1-5 were investigated.It was found that these corroles were able to photocleavage supercoiled pBR 322 DNA(SC) into nicked-circular DNA(NC).The activity of these corroles follows an order of 432≈15.The photosensitized singlet oxygen(Φ_△) quantum yield by these corroles also follows that same order,showing the photocleavage activity is related to the heavy atom effect of halogen atoms on corroles.     

Efficient synthetic methodology for the construction of dihydronaphthalene and benzosuberene molecular frameworks

Benzosuberene analogues (1 and 2) and dihydronaphthalene analogues (3 and 4) function as potent inhibitors of tubulin polymerization, demonstrate pronounced cytotoxicity (low nM to pM range) against human cancer cell lines, and are promising vascular disrupting agents (VDAs). As such, these compounds represent lead anticancer agents with potential translatability towards the clinic. Methodology previously established by us (and others) facilitated synthetic access to a variety of structural and functional group modifications necessary to explore structure activity relationship considerations directed towards the development of these (and related) molecules as potential therapeutic agents. During the course of these studies it became apparent that the availability of synthetic methodology to facilitate direct conversion of the phenolic-based compounds to their corresponding aniline congeners would be beneficial. Accordingly, modified synthetic routes toward these target phenols (benzosuberene 1 and dihydronaphthalene 3) were developed in order to improve scalability and overall yield [45-57% (1) and 32% (3)]. Moreover, benzosuberene-based phenolic analogue 1 and separately dihydronaphthalene-based phenolic analogue 3 were successfully converted into their corresponding aniline analogues 2 and 4 in good yield (>60% over three steps) using a palladium catalyzed amination reaction.     

Binary amorphous solids consisting of 2,4,6-triarylphenoxyl radicals and their dimers

Although molecular amorphous materials represent an important area of research in solid-state chemistry, studies pertaining to these systems have been restricted almost exclusively to amorphous solids based on a single molecule. In this study, we found that, while the 2,4,6-bis(4-tert-butylphenyl)phenoxyl radical (2_M) and its dimer (2_D) did not give single-component amorphous solids, they rapidly formed the corresponding binary amorphous solid IIa following their condensation from benzene, dichloromethane, chloroform, and ethyl acetate solutions. The formation of IIa could be attributed to the good solubilities of 2_M and 2_D in these solvents and the high packing efficiencies of these amorphous solids. IIa was also obtained when crystals of 2_D (IIb) were ground together. The solid-state formation of IIa would not only involve the locational exchange of 2_M and 2_D, but would also involve chemical exchanges.     

Facile synthesis and coupling of functionalized isomeric biquinolines

A simple route toward functionalized biquinolines, namely 8,5′-dibromo-5,8′-biquinoline 1 and 5,5′-dibromo-8,8′-biquinoline 2, was developed using Skraup syntheses. Both the dibromo compounds undergo facile Suzuki coupling to afford fluorene-coupled products 3 and 4, respectively, an important transformation in designing conjugated materials based on these cores. X-ray structural analyses of 1 and 4 provide insight into the mode of packing within materials containing these units.     

Dracomolphesin A–E,five 3,4-seco-phenylpropanoids with Nrf2 inducing activity from Dracocephalum moldavica

Dracomolphesin A–E (1–5), five 3,4-seco-phenylpropanoids featuring an aromatic ring opened framework, were isolated from the aerial parts of Dracocephalum moldavica. The structures with absolute configurations were determined by spectroscopic methods coupled with Mosher method. Notably, these compounds represented an example of aromatic ring cleavage products of phenylpropanoids. The possible biosynthetic pathway of these compounds was proposed. Compounds 1, 2, 4 and 5 were demonstrated to be Nrf2 pathway activators.     

Synthesis,structure and electronic properties of N-dialkylamino- and N-alkoxy-1,2,4-triazol-3-ylidene ligands

4-Amino- and 4-alkoxy-1,2,4-triazoles 4a–d and 6 were readily obtained from the reaction of N,N-dimethylformamidazin dihydrochloride 3 with hydrazines 2 and hydroxylamine 5. Alkylation of compounds 4a–d and 6 by MeOTf or MeI afforded azolium salts 9–11, which in turn were transformed into Rh(I) carbene complexes 13–15, Ag carbenes 16, and cationic Rh(I) bis-carbenes 17. Additionally, complexes 13 and 15 were transformed into dicarbonyl derivatives 18 and 19, and the carbonyl stretching frequencies of these compounds were used to evaluate the effect of the amino and alkoxy groups in the σ-donor ability of these 1,2,4-triazol-3-ylidenes.     

Biosynthetic studies in the coumarin series—I : Studies in plants of Thamnosma montana Torr. and Frem. the role of mevalonate

Investigations on the biosynthesis of the coumarins, umbelliprenin (1), isopimpinellin (2), alloimperatorin methyl ether (3) and isoimperatorin (4) are described. Extensive degradation studies on these systems have provided the opportunity to evaluate the various centers in these radioactive coumarins obtained from mevalonate incorporation. These results are discussed in the light of previous proposals.     

Infrared spectroscopic detection of sulphone groups in doped polybenzo[c]thiophenes

By reaction of 1,3-dihydrobenzo[c]thiophene with FeCl₃, air or TCNQ the oxidatively doped polybenzo[c]thiophenes (1a, b, d, e) were prepared. Their infrared spectra showed two strong absorptions in the ranges 1265–1337 cm⁻¹ and 1142–1184 cm⁻¹. Efficient drying did not change these absorptions but reaction of 1a, b, d, e with LiAlH₄ resulted in their decrease to weak bands. According to these results and by comparison with the infrared spectra of reference compounds data, 1a—e were found to contain sulphone groups.     

l-Idoseptanosides: substrates of d-glucosidases?

Based on the reported glycosidase inhibitory activities of 1,6-dideoxy-1,6-imino-l-iditol, the corresponding aryl glycosides 4-nitrophenyl α- and β-l-idoseptanoside 7 and 8 were synthesised as possible glycosidase substrates. Despite their inherently larger size, these septanosides were indeed shown to be glycosidase substrates, albeit weak ones. In addition, these two substrate analogues 7 and 8 also demonstrated a remarkable degree of selectivity for β- and α-glucosidases, respectively.     

Coumarins with an unprecedented tetracyclic skeleton and coumarin dimers from chemically engineered extracts of a marine-derived fungus

The unprecedented tetracyclic coumarin derivatives 1 and 2 and the coumarin dimers 3–5 were isolated from chemically engineered extracts (coumarin dimerization of natural extract) of the marine-derived fungus Eurotium rubrum. The structures of these compounds were established using NMR, MS and IR methods. The absolute configuration of 1 was determined by ECD calculations. The unprecedented tetracyclic coumarin skeleton was generated by domino-Knoevenagel-Diels-Alder reactions. Compounds 1–5 showed tyrosinase inhibitory activity (IC₅₀?=?1.7, 1.2, 4.9, 1.8 and 2.9?μM, respectively). The isolated coumarin derivatives 1–5 were not observed by HPLC analysis in crude extracts of E. rubrum, suggesting that chemically engineered extract generated these new coumarin derivatives with tyrosinase inhibitory activity.     

Synthesis and photochemistry of novel bromo substituted stilbene derivatives as triplet state sensitizers for the generation of singlet oxygen

We have presented the synthesis and characterization of three new bromo substituted stilbene derivatives,p-3,4,5-trimethoxy-p'- 2,3,4,5,6-pentabromostilbene(C1),p-N,N-dimethylamino-p'-2,3,4,5,6-pentabromostilbene(C2) and p-N,N-diphenylamino-p'- 2,3,4,5,6-pentabromostilbene(C3) in this letter.The UV/vis absorption and photoluminescence were investigated in various solvents.The maximal absorption wavelength of C1 exhibited blue-shift to those of C2 and C3 in different solvents.No florescence emission could...     

Carbocyclization in natural products—II : Brominative cyclization of dihydrocostunolide

Treatment of dihydrocostunolide 1 with NBS in aqueous acetone at room temperature furnished bromolactones 3, 4 and 5. Structural evidence for these bromolactones rests upon spectral data and chemical correlations with santanolide “c” 10. Mass spectral fragmentation patterns for the bromolactones, with special reference to 4, have been also discussed.     

Stereospecific synthesis of some polycyclic cis-β-lactams

Amides 1 on reaction with P₂S₅ in pyridine give thioamides 2 which on treatment with methyl iodide afford the corresponding 1-methylthio-3,4-dihydroisoquinolines 3. Annelation of these imines with phenoxyacetyl chloride in the presence of triethylamine furnish 6-methylthio-7-phenoxy-2',3' - dimethoxybenzo[a]octem 4a and 6-methylthio-7-phenoxy-2,3-methylenedioxybenzo[a]octem 4b respectively. Desulphurisation of these β-methylthio-β-lactams with Raney nickel yield the novel polycyclic cis-β-lactams 5a and 5b.     

Alcaloides du peripterygia marginata (baill.) lues. (célastracées)—I : Révision de la structure de la périphylline

Six new alkaloids, periphylline 1, isoperiphylline 5, dihydroperiphylline 21, neoperiphylline 22, perimargine 23 and dihydroperimargine 24 have been isolated from the leaves of Peripterygia marginata. All these alkaloids contain a thirteen-membered ring system derived from dicinnamoylspermidine.     

Synthesis and evaluation of new phosphonic,bisphosphonic and difluoromethylphosphonic acid monomers for dental application

Syntheses of novel 5-(methacryloyloxy)pentylphosphonic acid 1, 5-(methacryloyloxy)pentylidenebisphosphonic acid 2 and 1,1-difluoro-5-(methacryloyloxy)pentylphosphonic acid 3 are described. The ability of these monomers to adhere to hydroxyapatite was demonstrated using ³¹P CP-MAS NMR spectroscopy. Their copolymerization with N,N′-diethyl-1,3-bis(acrylamido)propane (DEBAAP) was investigated with photo differential scanning calorimetry. These mixtures exhibit a significantly higher reactivity than DEBAAP alone. Bisphosphonic acid 2 was shown to be significantly more reactive than monomers 1 and 3. Adhesive properties of these monomers were also studied. Adhesives based on bisphosphonic acid 2 and difluoromethylphosphonic acid 3 provide significantly higher dentin shear bond strength than the one based on phosphonic acid 1.     

Photochemistry of ethenobenzocycloheptenones : A Di-π-methane rearrangement of β,γ-unsaturated aryl ketones

Benzotropones 6 react with dienophiles 7 to give endo-adducts 8 as shown by PMR. Unlike similar ketones which usually undergo 1,3-acyl shifts or oxadi-π-methane rearrangements, these ethenobenzocycloheptenones 8, on direct or sensitized irradiation, lead to the di-π-methane rearrangement products 1H-benzo[f]cycloprop[cd]-indenones 9. The structures of the latter were elucidated by the use of Eu(FOD)₃ and X-ray diffraction. Prolonged irradiation of tetrahydrofluorenone 19 a potential 1,3-acyl shift product of ethenobenzocycloheptenones, gave only dienyl aldehyde 21 in low conversion. These results suggest that the chemical pathway chosen in these reactions is dependent on geometrical and electronic factors.     

Synthesis and rearrangement of 13-thiaprostanoids

Thiaprostanoids 13 were prepared by conjugate addition of mercaptane 6 to cyclopentenones 12 and 20. Novel rearrangements of these compounds to 14 and 15 were interpreted as enolate induced [1,5]-sigmatropic shift on the corresponding dehydration products 16. Preparation of the various substrates and structural elucidation of new products are described.     

A one-step conversion of isoquinolinium salts into naphthalene derivatives1

Berberine chloride (1) upon treatment with NaOAc-Ac₂O yields naphthalene derivatives 4 and 5 In like fashion, 8 gives naphthalene 10; isoquinoline methiodide leads to β-naphthyl acetate; and 12 provides 14. The reaction has been extended to the 3-carbonyl pyridinium series where 3-acetylpyridine methiodide and 3-pyridinecarboxaldehyde methiodide furnish lactones 16 and 17, respectively. All these transformations proceed by initial nucleophilic attack of the acetic anhydride anion on the immonium carbon atom.     

Zum mechanismus der reaktion von alkylierten aromaten mit dichlorcarben

Tropylium halides (type B) are not stable. When trying to prepare these from 4 resp. 7 subsequent products are obtained. Makosza reaction of 4 gives the same product 1 as from 2-methyl naphthaline. Thus, B is an intermediate.     

Computational and cyclic voltammetry studies of high effective-molarity assisted reversible reductions of [4]- and [5]heli-viologens: Potential building blocks for new materials

Computational and cyclic voltammetry studies have been used to explore electrochemical reductions of three helically chiral homologues, 2²⁺, 3²⁺, and 4²⁺, of methyl viologen. Thermochemical-electrochemical cycles are used as frameworks to describe the reversible redox properties of these helically chiral viologens as novel reversible four-sided ECEC (Electron-transfer Chemical-reaction Electron-transfer Chemical-reaction) processes.