Synthesis of 3‐Aryl‐2‐methoxyinden‐1‐one (Z)‐Phenylhydrazones via Hydrobromic Acid‐Mediated Cyclization of 2‐(1‐Aryl‐2‐methoxyethenyl)benzaldehyde Phenylhydrazones

2‐(1‐Aryl‐2‐methoxyethenyl)benzaldehydes 2 , obtained by successive treatment of 1‐(1‐aryl‐2‐methoxyethenyl)‐2‐bromobenzenes 1 with BuLi and 1‐formylpiperidine, were transformed to the corresponding phenylhydrazones 3 on treatment with PhNHNH₂. When these hydrazones were allowed to react with conc. HBr, cyclization, followed by dehydrogenation with air occurred, furnished 3‐aryl‐2‐methoxyinden‐1‐one (Z)‐phenylhydrazones 4 .     

Efficient Synthesis of 1-Deaza-6-methoxypurine-N9-β-2′-deoxyribonucleoside and Related DNA Building Blocks

An improved synthesis of the 2′-deoxyribonucleoside containing 1-deaza-6-methoxypurine as artificial nucleobase is described. By optimizing the conditions for the deprotection of p-toluoyl-protected 1-deaza-6-nitropurine 2′-deoxyribonucleoside, the isolated yield of the title compound could be increased from 15% to 90%. In addition, the synthesis and characterization of the corresponding 5′-(4,4′-dimethoxytrityl) (DMT) protected phosphoramidite, a potentially useful building block for the synthesis of artificial oligonucleotides, is reported. The title compound offers interesting hydrogen bond donor and metal-binding properties for its application in metal-mediated base pairs.

Furanone Derivatives from Aspergillus sp. XW‐12, an Endophytic Fungus in Huperzia serrata

Two new 5‐methoxyfuran‐3(2H)‐one derivatives, huaspenone A ( 1 ) and B ( 2 ), together with four known ones, i.e., aspertetronin A ( 3 ), aspertetronin B ( 4 ), gregatin E ( 5 ), and penicilliol A ( 6 ), were isolated from the cultures of an endophytic fungus Aspergillus sp. XW‐12, derived from the stems of Huperzia serrata. The structures of the new isolates were established by detailed interpretation of the 1D‐ and 2D‐NMR and HR‐ESI‐MS data.     

A new coumarin from Perezia hebeclada

Methanol extracts from Perezia hebeclada roots yielded the new 8‐β‐D ‐glucopyranosyloxy‐4‐methoxy‐5‐methylcoumarin ( 1 ) together with the known 4‐β‐D ‐glucopyranosyloxy‐5‐methylcoumarin ( 2 ). Their structures were determined and verified, respectively, by MS and NMR studies, including 1D and 2D experiments. Two ¹³C NMR signals of the sugar residue of 2 were reassigned. Copyright © 2003 John Wiley & Sons, Ltd.     

Chain composition dependence of luminescence properties for copolymers of 2‐methoxy‐5‐2′‐ethyl‐hexyloxy‐1,4‐phenylenevinylene and 2,3‐diphenyl‐5‐octyl‐1,4‐phenylenevinylene

The copolymers of 2‐methoxy‐5‐2′‐ethyl‐hexyloxy‐1,4‐phenylenevinylene (MEH‐PV) and 2,3‐diphenyl‐5‐octyl‐1,4‐phenylenevinylene were prepared via the Gilch route with their chain compositions and the reactivity ratios of the monomers estimated by ¹H NMR spectroscopy. The results indicated that the copolymers tended to form an alternative copolymer as the feed ratio of the monomers closed to one‐half. When an individual copolymer solution in tetrahydrofuran was spun‐cast to form a film, the MEH‐PV units were able to attract the like units from the adjacent chains. As a result, the ultraviolet–visible absorption spectrum of the alternative copolymer in film form was broader than the spectra of those with different compositions. The photoluminescence spectra of the copolymers in film form exhibited the characteristic shoulder of poly(2‐methoxy‐5‐2′‐ethyl‐hexyloxy‐1,4‐phenylenevinylene), even though the content of MEH‐PV units was not great enough for the formation of repeat units in sequence. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2180–2186, 2003     

Metal‐Catalyzed Dealkoxylative CarylC Cross‐Coupling—Replacement of Aromatic Methoxy Groups of Aryl Ethers by Employing a Functionalized Nucleophile

The direct replacement of aromatic methoxy groups with activated carbon nucleophiles would give rise to novel synthetic pathways for targeted and diversity‐oriented syntheses. We demonstrate here that this transformation can be achieved in a one‐step reaction involving a bifunctional organolithium nucleophile in combination with a C_Ar? OMe bond‐cleaving nickel catalyst. The resulting products are stable, α‐CH active, and suitable for various further modifications.     

A helical zinc(II) coordination polymer assembled from 1,3‐bis[(pyridin‐3‐yl)methoxy]benzene and benzene‐1,4‐dicarboxylic acid

In catena‐poly[[aqua[1,3‐bis(pyridine‐3‐ylmethoxy)benzene‐κN]zinc(II)]‐μ₂‐benzene‐1,4‐dicarboxylato‐κ²O¹:O⁴], [Zn(C₈H₄O₄)(C₁₈H₁₆N₂O₂)(H₂O)]_n, each Zn^II centre is tetrahedrally coordinated by two O atoms of bridging carboxylate groups from two benzene‐1,4‐dicarboxylate anions (denoted L²⁻), one O atom from a water molecule and one N atom from a 1,3‐bis[(pyridin‐3‐yl)methoxy]benzene ligand (denoted bpmb). (Aqua)O—H...N hydrogen‐bonding interactions induce the formation of one‐dimensional helical [Zn(L)(bpmb)(H₂O)]_n chains which are interlinked through (aqua)O—H...O hydrogen‐bonding interactions, producing two‐dimensional corrugated sheets.     

Enhancing the electroluminescent efficiency of poly{5‐methoxy‐2‐[(2′‐ethyl‐hexyl)‐oxy]‐p‐phenylenevinylene}/poly(2,3‐diphenyl‐5‐octyl‐p‐phenylenevinylene) polyblends by the introduction of chemical bonding through a thermal treatment

A significant improvement in the electroluminescence (EL) properties was observed for a poly{5‐methoxy‐2‐[(2′‐ethyl‐hexyl)‐oxy]‐p‐phenylenevinylene} (MEH–PPV)/poly(2,3‐diphenyl‐5‐octyl‐p‐phenylenevinylene) (DPO–PPV) blend after a thermal treatment at 200 °C for 2 h in vacuo to furnish the chemical bonding between polymer chains. ¹H NMR spectroscopy and two‐photon excitation microscopy revealed that the chemical bonding turned the immiscible polyblend into a system more like a block copolymer with a vertically segregated morphology. Because both the lowest unoccupied molecular orbital and highest occupied molecular orbital levels of MEH–PPV in the wetting layer were higher than those of DPO–PPV in the upper layer, the heterojunction between the two layers of the polymers fit the category of so‐called type II heterojunctions. As a result, the turn‐on voltage of the polymer light‐emitting diode prepared with the thermally treated polyblend decreased to ～0.6 V, and the EL emission intensities and quantum efficiencies increased to about 4 times those of the untreated polyblend. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 62–69, 2006     

Dependence of the luminescent properties and chain length of poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylene vinylene] on the formation of cis‐vinylene bonds during Gilch polymerization

The presence of cis‐vinylene bonds in Gilch‐polymerized poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylene vinylene] is reported. Through fractionation, species with a weight‐average molecular weight of less than 37,000 exhibited an abnormal blueshift of photoluminescence spectra in toluene solutions, and this was attributed to the presence of cis‐vinylene bonds, as verified by NMR spectroscopy. Surprisingly, the fractionated species (～1 wt %) with a weight‐average molecular weight of 5000 were mostly linked by the cis‐vinylene bonds. The concentration decreased with the molecular weight until a molecular weight of 37,000 was reached; at that point, the polymer chains contained mainly trans‐vinylene bonds. Obviously, the formation of cis‐vinylene bonds strongly inhibited the growth of polymer chains during Gilch polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2520–2526, 2005     

Total assignments of 1H and 13C NMR spectra of a new prenylated flavanone from Dioclea grandiflora

A new prenylated flavanone, floranol ( 1 ) 3,5,7,2′‐ tetrahydroxy‐6‐methoxy‐8‐prenylflavanone and a known flavanone (dioclein) were isolated from the roots of Dioclea grandiflora (Fabaceae). The structure and the relative stereochemistry were established by 2D NMR spectroscopic techniques (HMQC and HMBC) Copyright © 2002 John Wiley & Sons, Ltd.