Towards the syntheses of N‐H and N‐alkylated derivatives of meridianins

Novel N‐H and N‐alkylated derivatives of meridianins have been synthesized as potential antitumor agents by a two‐step conversion of N‐tosyl‐3‐acetylindoles or N‐alkyl‐3‐acetylindoles to the corresponding enaminones using DMF‐DMA, with or without added pyrrolidine. Further cyclization with guanidine gave the corresponding 2‐aminopyrimidines. The structures of the compounds, thus obtained, were proved by ¹H and ¹³C NMR spectroscopy, NOE experiments and X‐ray analysis.     

The influence of benzoate anion substituents on the crystal packing and hydrogen-bonding network of 9-aminoacridinium salts

As a continuation of our recent work, we discuss the crystal structures of a series of salts with the 9-aminoacridinium cation and 3-chlorobenzoate, 4-chlorobenzoate and 3-hydroxybenzoate anions. The crystal structure of [2(C₁₃H₁₁N₂⁺)·C₇H₅O₃⁻·Cl⁻·2(H₂O)] is the first of all the known 9-aminoacridinium salts where mixed salts were obtained. Analysis of the hydrogen bonds in the crystal lattices of the title compounds shows that the ions are linked via N(amino)-H?O(carboxy) hydrogen bonds forming R₂²(8) or R₂⁴(16) hydrogen bond ring motifs. In the packing, there are also two kinds of hydrogen bond chain motif. The first, C₄²(16), in which 9-AA cations, a Cl⁻ anion and a water molecule are interlinked, and the second, C(7), in which aromatic carboxylic acid anions are connected directly. We also observed the influence of the different anions on the packing of the acridine skeletons in the crystal lattice.     

Internal‐to‐Cartesian back transformation of molecular geometry steps using high‐order geometric derivatives

In geometry optimizations and molecular dynamics calculations, it is often necessary to transform a geometry step that has been determined in internal coordinates to Cartesian coordinates. A new method for performing such transformations, the high‐order path‐expansion (HOPE) method, is here presented. The new method treats the nonlinear relation between internal and Cartesian coordinates by means of automatic differentiation. The method is reliable, applicable to any system of internal coordinates, and computationally more efficient than the traditional method of iterative back transformations. As a bonus, the HOPE method determines not just the Cartesian step vector but also a continuous step path expressed in the form of a polynomial, which is useful for determining reaction coordinates, for integrating trajectories, and for visualization. © 2013 Wiley Periodicals, Inc.     

The effect of the N‐substituent s‐trans to the carbonyl group of N‐methylacrylamide derivatives on the stereospecificity of radical polymerizations

Radical polymerization of N‐methylacrylamide (NMAAm), N,N‐dimethylacrylamide (DMAAm), and N‐methyl‐N‐phenylacrylamide (MPhAAm) was investigated in toluene at low temperatures. Atactic, isotactic, and syndiotactic polymers were obtained by the polymerization of NMAAm, DMAAm, and MPhAAm, respectively, indicating that the stereospecificity of the radical polymerization of acrylamide derivatives depended on the N‐substituents of the monomer used. From the viewpoint of monomer structure, the origin of the stereospecificity of radical polymerization of NMAAm derivatives is discussed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6534–6539, 2009     

Derivatives of some cyclic 3,4‐quinolinediyl bis‐sulfides with N,N‐dimethylcarbamoyl and N‐methyl‐N‐formylaminornethyl substituents in the 2‐quinolinyl position

Reactions of hydrogen sulfates of quino‐ and diquino‐annelated 1,4‐dithiins 11 and 2 with DMF/hydroxylamine‐O‐sulfonic acid/Fe⁺⁺ ion system took place at the α‐quinolinyl positions and led to N,N‐dimethylcarbamoyl and N‐methyl‐N‐formylaminomethyl derivatives 6 , 8 , 12 and 7 , 9 , 13 , respectively. The ¹H and ¹³C NMR spectra of N‐methyl‐N‐formylaminomethyl derivatives 7 , 9 , 13 showed the presence of rotational isomers E and Z regarding to the N‐methyl‐N‐formylaminomethyl substituent. The spectra of 6 , 7 , 8 , 12 and 13 were completely assigned with the use of 1D and 2D NMR techniques. In the case of rotational isomers 7a and 7b , the crucial correlations came from the NOE interaction between the methylene and methyl protons from CH₂N(CH₃)CHO groups and benzene‐rings protons. Synthesis of 2,3‐dihydro‐1,4‐dithiino[6,5‐e]quinoline 4‐oxide 14 was presented as well.     

Synthesis and insecticidal evaluation of N‐tert‐butyl‐N′‐thio[O‐(1‐methylthioethylimino)‐N″‐methylcarbamate]‐N,N′‐diacylhydrazines

A series of novel N‐tert‐butyl‐N′‐thio[O‐(1‐methylthioethylimino)‐N″‐methylcarbamate]‐N,N′‐diacylhydrazines were synthesized by the reaction of chlorosulfenyl[O‐(1‐methylthioethylimino)‐N‐methylcarbamate] with N‐tert‐butyl‐N,N′‐diacylhydrazine in the presence of sodium hydride. The reaction of sulfur dichloride with O‐(1‐methylthioethylimino)‐N‐methylcarbamate (Methomyl) in the presence of pyridine to yield chlorosulfenyl[O‐(1‐methylthioethylimino)‐N‐methylcarbamate] was reported for the first time. X‐ray single crystal diffraction of N‐tert‐butyl‐N′‐thio[O‐(1‐methylthioethylimino)‐N″‐methylcarbamate]‐N,N′‐dibenzoylhydrazine demonstrated that the parent compounds N‐tert‐butyl‐N,N′‐dibenzoylhydrazine and O‐(1‐methylthioethylimino)‐N‐methylcarbamate were combined by N S N band to give the product. Their larvicidal activities against Oriental armyworm and Aphis laburni were evaluated. All of them exhibited excellent larvicidal activities against Oriental armyworm, with some of them showing higher larvicidal activities than the parent diacylhydrazines. Toxicity assays indicated that the products show knockdown activity for O‐(1‐methylthioethylimino)‐N‐methylcarbamate at higher concentration and insect growth regulators' activities of diacylhydrazines at lower concentrations. At the same time, the products possess insecticidal activities against the aphids. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:631–636, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20360     

Radical polymerization of novel N‐substituted‐N‐vinylformamide derivatives with bulky chiral substitutents

A series of novel N‐substituted‐N‐vinylformamides were synthesized, and the effect of bulky substituents on their radical polymerizability and polymer structure were investigated. N‐(p‐Methoxybenzyl)‐N‐vinylformamide ( 3 ) and N‐cyclohexylmethyl‐N‐vinylformamide ( 4 ) generated polymers, while it was known that their N‐vinylacetamide derivatives did not. ¹H NMR and ¹³C NMR analyses of poly( 3 ), however, revealed almost no difference among the various polymerization conditions, implying that the substituent bulkiness did not influence the polymer structures. On the other hand, the chiral polymers, which were obtained by the radical polymerization of N‐(S)‐2‐methylbutyl‐N‐vinylformamide ((S)‐ 5 ) and N‐(S)‐2,3‐dihydroxypropyl‐N‐vinylformamide ((S)‐ 7 ) at 0 °C, showed sharper spectral patterns than those obtained at higher polymerization temperatures. Furthermore, the intensities of their positive cotton effects on circular dichroism increased when the polymerization temperature was low, suggesting that the substituent bulkiness of (S)‐ 5 and (S)‐ 7 influenced the polymer structures, such as their stereoregularity and regioregularity. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Solvent influence on the crystal packing of 6‐aminothiocytosine

The crystal structures of 6‐aminothiocytosine (systematic name: 4,6‐diamino‐1,2‐dihydropyrimidine‐2‐thione, DAPMT, C₄H₆N₄S), its hemihydrate (0.5H₂O) and its dimethylformamide (DMF, C₃H₇NO) monosolvate were compared, and the influence of the type of solvent on the supramolecular motifs was analysed. In all three crystal structures, there are two symmetry‐independent molecules (A and B), and these molecules are connected by three relatively short and directional hydrogen bonds to form chains of alternating A and B molecules. A further organization of these chains is dependent on the nature of the solvent molecule. In the unsolvated form, two orientations of the neighbouring chains are observed, and similar motifs – but only one per structure – can be observed in the solvated structures. These two different motifs can be connected by two different kinds of contacts, i.e. either π–π (hemihydrate) or staple‐supported S…S (DMF). In the crystal structures, the O atoms of the solvent molecules are double acceptors of the same type of hydrogen bonds and bind the chains of DAPMT molecules into different motifs (dimeric or infinite chains). A Hirshfeld fingerprint analysis was used for visualization and additional interpretation of these results.     

Hydrogen‐bond‐assisted syndiotactic‐specific radical polymerizations of N‐alkylacrylamides: The effect of the N‐substituents on the stereospecificities and unusual large hysteresis in the phase‐transition behavior of aqueous solution of syndiotactic poly(N‐n‐propylacrylamide)

The radical polymerizations of N‐alkylacrylamides, such as N‐methyl‐(NMAAm), N‐n‐propyl‐(NNPAAm), N‐benzyl‐(NBnAAm), and N‐(1‐phenylethyl)acrylamides (NPhEAAm), at low temperatures were investigated in the absence or presence of hexamethylphosphoramide (HMPA) and 3‐methyl‐3‐pentanol (3Me3PenOH), which induced the syndiotactic specificities in the radical polymerization of N‐isopropylacrylamide (NIPAAm). In the absence of the syndiotactic‐specificity inducers, the syndiotacticities of the obtained polymers gradually increased as the bulkiness of the N‐substituents increased. Both HMPA and 3Me3PenOH induced the syndiotactic specificities in the NNPAAm polymerizations as well as in the NIPAAm polymerizations. The addition of 3Me3PenOH into the polymerizations of NMAAm significantly induced the syndiotactic specificities, whereas the tacticities of the obtained polymers were hardly affected by adding HMPA. In the polymerizations of bulkier monomers, such as NBnAAm and NPhEAAm, HMPA worked as the syndiotactic specificity inducer at higher temperatures, whereas 3Me3PenOH hardly influenced the stereospecificity, regardless of the temperatures. The phase‐transition behaviors of the aqueous solutions of poly(NNPAAm)s were also investigated. It appeared that the poly (NNPAAm) with racemo dyad content of 70% exhibited unusual large hysteresis between the heating and cooling processes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4575–4583, 2008     

The influence of molecular geometry on the fluorescence spectra of biphenyl and the polyphenyls

The shapes of the fluorescence spectra of rigid solutions (in ethanol at 77 K) of biphenyl,p-terphenyl, andp-quaterphenyl are shown to depend on the wavelength of the exciting light: the spectral resolution enhances with increasing wavelength of excitation. These spectra are interpreted in terms of a model wherein the equilibrium configuration of the fluorescent state is planar, but that of the ground state deviates from planarity.Some other results reported in the literature are also discussed and it is concluded that the ground states of the singly and doubly charged ions of these molecules, as well as the lowest triplet states of the neutral molecules, are nearly planar.     

N‐Germyl derivatives of sulfacetamide and ortho‐(sulfonamido)phenylamines: characterization of N‐[o‐(N′,N′‐dimethylsulfonamido)phenyl]‐N‐dimesitylgermaimine

Triethylgermylation of sulfacetamide occurs on the sulfonamido nitrogen in competition with the 1,2 addition of the starting triethylgermyl dimethylamine on the carbonyl group. Thermal decomposition in the presence of dimethylamine yields N‐triethylgermylsulfanilamide. Stable 1:1 sulfacetamide–DBU and 1:1 sulfacetamide–Et₃N complexes were isolated and fully characterized in the course of dehydrochlorination reactions. o‐Sulfonamidophenylamine yields N,N′‐bis‐triethylgermylated derivatives, whereas o‐(N,N‐dimethylsulfonamido)phenylamine leads to monogermylated compounds. The N‐dimethylaminodimesitylgermyl derivative is thermally stable. Dehydrohalogenation of the N‐dimesitylfluorogermyl compound leads to the thermally stable but water sensitive N‐[o‐(N′,N′‐dimethylsulfonamido)phenyl]‐N‐dimesitylgermaimine. Copyright © 2003 John Wiley & Sons, Ltd.     

Influence of the position of the methyl substituent and N‐oxide formation on the geometry and intermolecular interactions of 1‐(phenoxyethyl)piperidin‐4‐ol derivatives

Aminoalkanol derivatives have attracted much interest in the field of medicinal chemistry as part of the search for new anticonvulsant drugs. In order to study the influence of the methyl substituent and N‐oxide formation on the geometry of molecules and intermolecular interactions in their crystals, three new examples have been prepared and their crystal structures determined by X‐ray diffraction. 1‐[(2,6‐Dimethylphenoxy)ethyl]piperidin‐4‐ol, C₁₅H₂₃NO₂, 1 , and 1‐[(2,3‐dimethylphenoxy)ethyl]piperidin‐4‐ol, C₁₅H₂₃NO₂, 2 , crystallize in the orthorhombic system (space groups P2₁2₁2₁ and Pbca, respectively), with one molecule in the asymmetric unit, whereas the N‐oxide 1‐[(2,3‐dimethylphenoxy)ethyl]piperidin‐4‐ol N‐oxide monohydrate, C₁₅H₂₃NO₃·H₂O, 3 , crystallizes in the monoclinic space group P2₁/c, with one N‐oxide molecule and one water molecule in the asymmetric unit. The geometries of the investigated compounds differ significantly with respect to the conformation of the O—C—C linker, the location of the hydroxy group in the piperidine ring and the nature of the intermolecular interactions, which were investigated by Hirshfeld surface and corresponding fingerprint analyses. The crystal packing of 1 and 2 is dominated by a network of O—H…N hydrogen bonds, while in 3 , it is dominated by O—H…O hydrogen bonds and results in the formation of chains.     

The influence of electron deficient unit and interdigitated packing shape of new polythiophene derivatives on organic thin‐film transistors and photovoltaic cells

A series of new polythiophene derivatives containing a thiazole ring as an electron deficient unit were successfully synthesized via Stille coupling reactions. Synthesized polymers were classified into two types (H‐shape packing and A‐shape packing) based on their interdigitated packing structure induced by different side chain configurations. The thiophene derivatives that contained a thiazole unit ( PT50Tz50 , PTz100 , and PTTz ) exhibited much better thermal stability than did the full thiophene polymers ( PT100 and PTT ). The polymers containing the thiazole unit ( PTz100 and PTTz ) showed a red‐shifted absorption spectrum with clear vibronic structure. In addition, the XRD and AFM results showed that the polymers containing the thiazole unit and interdigitated H‐shape exhibited much better ordered and connected intermolecular structures than did other polymers. The improved intermolecular ordering and surface morphologies directly facilitated charge carrier transport in thin film transistor (TFT) devices, without introducing charge traps, and yielded higher solar cell performance. Among these polymers, the PTTz copolymer exhibited the best TFT performance (μ = 0.050 cm² V^?1 s^?1, on/off ratio = 10⁶, and V_th = ?2 V) and solar cell performance (PCE = 1.39%, J_sc = 6.58 mA cm^?2, and V_oc = 0.58 V). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Reaction of thio and seleno phosphoric acid derivatives with O‐thioacylated hydroxylamine

The reactivity of thio and seleno analogs of phosphoric acid 1b–f with O‐thioacylhydroxylamine 2 was examined. The experimental evidence for the proposed mechanism involving an N—O bond cleavage and a single electron transfer process (SET) from phosphate anions was collected. The influence of phosphoric acids 1 structure and their oxidation potentials on the course of the reaction and products 3, 4, 6, 7 distribution was presented. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:767–773, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20368     

Comparative study on the enzymatic polymerization of N‐substituted aniline derivatives

A series of water‐soluble N‐substituted poly(alkylanilines) (PNAAs) have been enzymatically synthesized with a variety of groups, from methyl to n‐butyl, such as poly(N‐methylaniline), poly(N‐ethylaniline), poly(N‐butylaniline) and poly(N‐phenylethanolamine). The syntheses were made in the presence of poly(4‐sodium styrene sulfonate) (SPS) as a template and horseradish peroxidase (HRP) as a catalyst. The size and type of the groups have a great effect on the properties of the final polymers. UV‐vis spectroscopy and cyclic voltammetry measurements confirmed that for enzymatically synthesized PNAAs/SPS complexes, the electroactivity increased with the bulkiness of the substituents. These polymers have been studied in the doped and undoped states by FT‐IR and UV‐vis spectroscopy. Also these polymers show multiple and reversible optical transitions that can be ascribed to the formation of polaron and bipolaron states. Copyright © 2005 John Wiley & Sons, Ltd.     

Substituent position effect on the crystal structures of N‐phenyl‐2‐phthalimidoethanesulfonamide derivatives

In order to determine the impact of different substituents and their positions on intermolecular interactions and ultimately on the crystal packing, unsubstituted N‐phenyl‐2‐phthalimidoethanesulfonamide, C₁₆H₁₄N₂O₄S, (I), and the N‐(4‐nitrophenyl)‐, C₁₆H₁₃N₃O₆S, (II), N‐(4‐methoxyphenyl)‐, C₁₆H₁₆N₃O₆S, (III), and N‐(2‐ethylphenyl)‐, as the monohydrate, C₁₈H₁₈N₂O₄S·H₂O, (IV), derivatives have been characterized by single‐crystal X‐ray crystallography. Sulfonamides (I) and (II) have triclinic crystal systems, while (III) and (IV) are monoclinic. Although the molecules differ from each other only with respect to small substituents and their positions, they crystallized in different space groups as a result of differing intra‐ and intermolecular hydrogen‐bond interactions. The structures of (I), (II) and (III) are stabilized by intermolecular N—H…O and C—H…O hydrogen bonds, while that of (IV) is stabilized by intermolecular O—H…O and C—H…O hydrogen bonds. All four structures are of interest with respect to their biological activities and have been studied as part of a program to develop anticonvulsant drugs for the treatment of epilepsy.     

Role of weak C—H…O and strong N—H…O intermolecular interactions on the high‐symmetry molecular packing of trans‐cyclohexane‐1,4‐dicarboxamide

An unpredicted fourfold screw N—H…O hydrogen bond C(4) motif in a primary dicarboxamide (trans‐cyclohexane‐1,4‐dicarboxamide, C₈H₁₄N₂O₂) was investigated by single‐crystal X‐ray diffraction and IR and Raman spectroscopies. Electron‐density topology and intermolecular energy analyses determined from ab initio calculations were employed to examine the influence of weak C—H…O hydrogen‐bond interactions on the peculiar arrangement of molecules in the tetragonal P4₃2₁2 space group. In addition, the way in which the co‐operative effects of those weak bonds might modify their relative influence on molecular packing was estimated from cluster calculations. Based on the results, a structural model is proposed which helps to rationalize the unusual fourfold screw molecular arrangement.     

Intermolecular C—F...H—C contacts in the molecular packing of three isostructural N‐(fluorophenyl)mannopyranosylamines

Among the three compounds reported here, namely N‐(4‐fluorophenyl)‐β‐d ‐mannopyranosylamine, (I), N‐(3‐fluorophenyl)‐β‐d ‐mannopyranosylamine, (II), and N‐(2‐fluorophenyl)‐β‐d ‐mannopyranosylamine, (III), all with chemical formula C₁₂H₁₆FNO₅, (I) and (II) are isostructural, whereas (III) assumes the same packing arrangement as the unfluorinated analogue N‐phenyl‐β‐d ‐mannopyranosylamine, (IV), which has been reported previously. Similarities with respect to the intermolecular hydrogen‐bonding patterns exist across the series (I)–(III). A packing motif that distinguishes the shared packing arrangement of (I) and (II) from that of (III) is a C—F...H—C chain of graph set C(4) that is preserved in the formal exchange of F and H atoms at the 4‐ and 3‐positions on the aromatic ring of (I) and (II), but is replaced by a different chain of graph set C(5) when the F atom is located at the 2‐position of the aromatic ring in (III). The steric role of the F atom in (I)–(III) is ambiguous but is examined here in detail.     

2,4‐Dibromo‐3‐methoxy‐6‐nitrobenz­aldeyde: effect of substituents on ring geometry

In the title compound, C₈H₅Br₂NO₄, the endocyclic angles of the ring deviate significantly from the ideal value of 120°. The substituents deviate from the plane of the ring, with large twist angles for the aldehyde, nitro and methoxy groups. The geometry of the mol­ecule in the crystal is compared with that of the isolated mol­ecule, as given by a self‐consistent field molecular‐orbital Hartree–Fock calculation. Only weak hydrogen bonds of the C—H?Br and C—H?O types are present in the crystal structure.