N‐(2‐Bromoethyl)‐4‐piperidino‐1,8‐naphthalimide and N‐(3‐bromopropyl)‐4‐piperidino‐1,8‐naphthalimide

N‐(2‐Bromoethyl)‐4‐piperidino‐1,8‐naphthalimide, C₁₉H₁₉BrN₂O₂, (I), and N‐(3‐bromopropyl)‐4‐piperidino‐1,8‐naphthalimide, C₂₀H₂₁BrN₂O₂, (II), are an homologous pair of 1,8‐naphthalimide derivatives. The naphthalimide units are planar and each piperidine substituent adopts a chair conformation. This study emphasizes the importance of π‐stacking interactions, often augmented by other contacts, in determining the crystal structures of 1,8‐naphthalimide derivatives.     

Two polymorphs of 1,8‐dichloroanthracene

A second, monoclinic, polymorph of the title compound, C₁₄H₈Cl₂, has been found. In addition to the structure of this monoclinic form, the structure of the previously described orthorhombic form [Desvergne, Chekpo & Bouas‐Laurent (1978). J. Chem. Soc. Perkin Trans. 2, pp. 84–87; Benites, Maverick & Fronczek (1996). Acta Cryst. C 52 , 647–648] has been redetermined at low temperature and using modern methods. The low‐temperature structure of the orthorhombic form is of significantly higher quality than the previously published structure and additional details can be derived. A comparison of the crystal packing of the two forms with a focus on weak intermolecular C—H...Cl interactions shows the monoclinic structure to have one such interaction linking the molecules into infinite ribbons, while two crystallographically independent C—H...Cl interactions give rise to an interesting infinite three‐dimensional network in the orthorhombic crystal form.     

Synthesis of 10‐amino‐9‐aryl‐2,3,4,5,6,7,9,10‐octahydroacridine‐1,8‐dione derivatives

A series of novel 10‐amino‐9‐aryl‐2,3,4,5,6,7,9,10‐octahydroacridine‐1,8‐dione derivatives 4 were synthesized by hydrazine or phenylhydrazine and 9‐aryl‐1,8‐dioxo‐2,3,4,5,6,7,9‐heptahydroxanthene derivatives 3 , which were prepared by 5‐substituted‐1,3‐cyclohexanedione 1 and aromatic aldehydes 2 in the presence of concentrated H₂SO₄ as a catalyst in water. The structures of all compounds were characterized by IR, MS, ¹H‐NMR, and elemental analysis, and the title compounds possess good fluorescence properties. J. Heterocyclic Chem., (2012).     

New 1,8‐peri‐annelated tricyclic quinolone antibacterials

The synthesis of new tricyclic quinolones, resulting from peri‐annelation of 1,2,4‐oxadiazine moiety at the N‐1/C‐8 position of the pharmacophoric quinolone nucleus, are described. None of the synthesized compounds showed interesting antibacterial activity in vitro against the tested strains, with the exception of Klebsiella pneumoniae which was susceptible to all the compounds at MIC values of 8 μg/ml.     

Elaboration of 1,8‐naphthyridine‐2,7‐dicarboxaldehyde into novel 2,7‐dimethylimine derivatives

The known 1,8‐naphthyridine‐2,7‐dicarboxaldehyde was prepared by SeO₂ oxidation of 2,7‐dimethyl‐1,8‐naphthyridine. The dimethylated naphthyridine molecule was assembled from an adaptation of the Skraup synthesis using 2‐amino‐6‐methylpyridine and crotonaldehyde to afford a reproducible 37% yield, and constitute a significant advance over the literature of this reaction. The condensation of 1,8‐naph‐thyridine‐2,7‐dicarboxaldehyde with various primary amines (R = ‐C₆H₁₁, ‐CH₂C₆H₅, ‐C(CH₃)₃, ‐C₁₀H₁₅, and CH₂CH₂SCH₂CH₃) in alcohol affords diimines 1(a‐e) . The inherent crystallinity of 1(a‐e) affords pure compounds in reasonable to excellent yields (ca. 70%) after evaporation of solvent and recrystallization. The anticipated spectroscopic features of (N=C‐H) ¹H nmr shift and v(C=N) in the ir spectrum appear around 8.50 δ and 1640 cm^?1, respectively, for the series 1(a‐e) . These novel naph‐thyridines typically display the signature ¹H nmr doublets at ca. 8.15‐8.30 δ ascribed to the 3 and 4 naphthyridine protons, consistent with a mirror plane (through the quaternary carbons) perpendicular to the naphthyridine plane, and syn, syn relationships of the naphthyridine moiety with each imine nitrogen lone pair. Complexation studies of 1(a‐e) with transition metals of biological relevance such as copper(I) and copper(II) will be reported elsewhere.     

()‐9‐(2‐Bromophenyl)‐7,7‐dimethyl‐1,3,4,5,6,7,8,9‐octahydrofuro[3,4‐b]quinoline‐1,8‐dione

The title compound, C₁₉H₁₈BrNO₃, has potential calcium modulatory properties. The 1,4‐di­hydro­pyridine ring has a very shallow boat conformation and is one of the most planar examples of this moiety. The 2‐bromo­phenyl substituent is in the axial synperiplanar orientation. The quinoline ring has a half‐chair conformation, with the unusual arrangement of the out‐of‐plane atom being on the opposite side of the ring plane to the bromo­phenyl substituent. The mol­ecules are linked into chains by intermolecular hydrogen bonds.     

Poly[μ‐aqua‐μ4‐naphthalene‐1,8‐dicarboxylato‐zinc(II)]

In the title complex, [Zn(C₁₂H₆O₄)(H₂O)]_n, a Zn^II polymer based on naphthalene‐1,8‐dicarboxylate (1,8‐nap), the Zn^II atoms adopt an elongated octahedral coordination geometry. A zigzag chain is formed by μ₂‐aqua ligands and μ₂‐carboxylate groups of the 1,8‐nap ligands. Adjacent parallel chains are further linked by 1,8‐nap ligands, forming a twisted two‐dimensional layer structure along the (100) plane.     

An efficient and green preparation of 9‐arylacridine‐1,8‐dione derivatives

9‐Arylacridine‐1,8‐dione derivatives were prepared in an ionic liquid medium in the presence of CeCl₃ ċ 7H₂O through an one‐pot procedure. The method presented here has the advantages of environmental benignancy, good‐to‐excellent yields, and simple operational procedure. Moreover, the solvent and catalyst can be easily recovered and reused for several runs without obvious loss of activity. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:786–790, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20410     

10‐(4‐Fluorophenyl)‐3,3,6,6,9‐pentamethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione and 10‐(4‐fluorophenyl)‐3,3,6,6‐tetramethyl‐9‐­propyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione

10‐(4‐Fluoro­phenyl)‐3,3,6,6,9‐penta­methyl‐3,4,6,7,9,10‐hexa­hydro­acridine‐1,8(2H,5H)‐dione, C₂₄H₂₈FNO₂, (I), crystallizes with two crystallographically independent mol­ecules (which differ slightly in conformation), while 10‐(4‐fluoro­phenyl)‐9‐propyl‐3,3,6,6‐tetra­methyl‐3,4,6,7,9,10‐hexa­hydro­acridine‐1,8(2H,5H)‐dione, C₂₆H₃₂FNO₂, (II), crystallizes with one mol­ecule per asymmetric unit. In both structures, the central ring in the acridine moiety is in a sofa conformation, while the outer rings adopt intermediate half‐chair/sofa conformations. The central pyridine ring is orthogonal to the substituted phenyl ring. In both structures, the packing of the crystal is stabilized by C—H?O intermolecular hydrogen bonds.     

Synthesis of 9‐[1‐benzyl‐5‐(alkylsulfonyl)‐1H‐2‐imidazolyl]perhydro‐1,8‐acridinediones

Tricyclic dihydropyridines like ZM244085 are potential K_ATP channel openers. In this study 3‐cyanophenyl ring of ZM244085 was replaced with imidazolyl ring. So, 9‐[1‐benzyl‐5‐(alkylsulfonyl)‐1H‐2‐imidazolyl]perhydro‐1,8‐acridinediones ( 5d‐f ) were synthesized from 2‐alkylsulfonyl‐1‐benzyl‐5‐formylimidazole ( 4d‐f ) and cyclohexane‐1,3‐dione according to classical Hantzch synthesis as potential potassium channel modulators.     

9‐Benzoyl‐3,3,6,6‐tetramethyl‐1,2,3,4,5,6,7,8‐octahydroxanthene‐1,8‐dione: molecular conformation and supramolecular aggregation in xanthenediones

In the title compound, C₂₄H₂₆O₄, (I), the central ring of the fused tricyclic ring system adopts a shallow boat conformation, while the two outer rings adopt envelope conformations. The molecules are linked into C(9) chains by a single C—H...O hydrogen bond. The significance of this study lies in its comparison of the conformation and supramolecular aggregation of (I) with those of related compounds in the published literature.     

Ethyl 1,4‐Dihydro‐4‐oxo‐1,8‐naphthyridine‐3‐carboxylates by a Tandem SNAr‐Addition‐Elimination Reaction

A series of N‐substituted 1,4‐dihydro‐4‐oxo‐1,8‐naphthyridine‐3‐carboxylate esters has been prepared in two steps from ethyl 2‐(2‐chloronicotinoyl)acetate. Treatment of the β‐ketoester with N,N‐dimethylformamide dimethyl acetal in N,N‐dimethylformamide (DMF) gave a 95% yield of the 2‐dimethylaminomethylene derivative. Subsequent reaction of this β‐enaminone with primary amines in DMF at 120^oC for 24 h then afforded the target compounds in 47–82% yields by a tandem S_NAr‐addition‐elimination reaction. Synthetic and procedural details as well as a mechanistic rationale are presented.     

Dialkylaluminium‐, ‐Gallium‐, and ‐Indium‐Based Poly‐Lewis Acids with a 1,8‐Diethynylanthracene Backbone

Potential host systems based on a rigid 1,8‐diethynylanthracendiyl backbone were synthesised by treatment of 1,8‐diethynylanthracene with the Group 13 trialkyls AlMe₃, GaMe₃, InMe₃, AlEt₃ and GaEt₃. The resulting products were characterised by IR and multinuclear NMR spectroscopy, elemental analyses and determination of their crystal structures by X‐ray diffraction. The compounds are dimeric in the solid state and comprise two M₂C₂ heterocycles. Depending on the steric demand of the alkyl substituents at the metal atom, different types of binding modes were observed, which can be classified to lie between the ideals of side‐on coordination with almost linear primary M? C?C units and the 3c–2e coordination with symmetrically bridging alkynyl units in M‐C‐M bonds. As a solution in THF the dimers are broken into monomers and some are found to undergo ligand scrambling reactions.     

4,5,6,8,9‐Penta­chloro­pyrimido­[1,2‐a][1,8]­naphthyridin‐10‐one

The title compound, C₁₁H₂Cl₅N₃O, crystallizes in the monoclinic system with two mol­ecules in the asymmetric unit. The mol­ecules are chemically identical but have different structural parameters. In the three‐dimensional packing, the mol­ecules are arranged in dimers that are connected by slipped π–π stacking, and these dimers are connected to one another through several C—H·O and Cl·Cl interactions.     

Synthesis and characterization of new π‐conjugated polymers containing 1,8‐naphthyridine in the main chain: Role of the 1,8‐naphthyridine unit in π‐conjugated polymers

Alternating π‐conjugated copolymers of 1,8‐naphthyridine‐2,6‐diyl ( 1,8‐Nap ) with 9,9‐dioctylfluorene‐2,7‐diyl ( P(Flu‐Ph‐1,8‐Nap) ) and 2,5‐didodecyloxy‐1,4‐phenylene ( P(ROPh‐Ph‐1,8‐Nap) ) have been synthesized by Pd‐catalyzed organometallic polycondensation. The copolymers showed UV‐vis absorption peaks at around 390 nm in o‐dichlorobenzene. The polymers were photoluminescent both in o‐dichlorobenzene and in the solid state. In o‐dichlorobenzene, the emission peaks of P(Flu‐Ph‐1,8‐Nap) and P(ROPh‐Ph‐1.,8‐Nap) appeared at λ_EM = 440 and 471 nm, with quantum yields of 87% and 66%, respectively. Electrochemical data revealed that 1,8‐Nap behaved as a typical electron‐accepting unit. When P(Flu‐Ph‐1,8‐Nap) was treated with 10‐camphorsulfonic acid, the emission peak shifted to λ_EM = 598 nm. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Determination of Selenium with a Poly(1,8‐diamino‐naphthalene)‐Modified Electrode

The performance of a poly(1,8‐diaminonaphthalene)‐modified electrode for the determination of the Se(IV) ion in an aqueous medium was investigated with anodic stripping voltammetry without the pretreating of the sample. The experimental parameters for the analysis of Se(IV) were optimized and the characteristics of this polymer‐modified electrode were investigated by using cyclic voltammetry. The Se(IV) ions were chemically deposited onto the surface of the pDAN‐Au electrode in an acidic medium. The detection limit employing the anodic stripping differential pulse voltammetry was 9.0×10^?9 M for Se(IV) with 4.4 % of RSD. Satisfactory result for the determination of Se(IV) was acquired employing a certified standard urine reference material, SRM's 2670 (trace element in urine) with 4.1 ppb of SD.