Über die Reaktionen von Guanidin bzw. Thioharnstoff mit α,β,γ,δ-ungesättigten Ketonen

Guanidine and phenylguanidine react with phenylhexadienone1b and 1,5-diaryl-2,4-pentadien-1-ones1c–k respectively (via unstable dihydropyrimidines of type2 as intermediates) to 4-methyl- and 4-aryl-6-styryl-2-pyrimidinamines3b–j and N²-phenyl-2-pyrimidinamines7c, k. Efforts to stabilize the intermediates2 by introduction of electron-withdrawing substituents (compare^2,3) were not successful. Similarly, thiourea reacts with diphenylpentadienone1c to afford (via8c) 4-phenyl-6-phenethylpyrimidinethione9c. Action of guanidine on 1,3,5-triphenylpentadienone101 and on the 5-(3-chlorophenyl) analogue10m under decomposition of the ketones yields 4,6-diphenyl-and 4-(3-chlorophenyl)-6-phenyl-2-pyrimidineamine (121 andm), respectively. The formation of12m proves that acetophenone splits off from101,m during the reactions. However, heating of thiourea with10m in sodium butylate/butanol gives the expected 4,6-diphenyl-4-styryldihydropyrimidinethione13m. The reaction of thiourea with triphenylpentadienone101 is taking an atypical course: Addition of thiourea to the δ- and β-carbon atom of101 affords 2-(4,6-diphenyl-2-thioxohexahydro-4-pyrimidinyl)acetophenone (141); the conformation of the latter was deduced from¹H-NMR data.     

Pyrindinchemie, 2. Mitt.: Über die Synthese des 5,6-Dihydro-2-pyrindin-7-ons

The reaction of cinchomeronic anhydride with diethyl malonate in acetic anhydride in the presence of triethylamine yields1, which is hydrogenated over Pd/C (10%) in dry benzene to2. The structures of1 and2 are confirmed by IR-and¹H-NMR-spectra.1 can be reduced to3 with Zn in acetic acid. Hydrolysis of3 yields4, which is easily decarboxylated to5. Methylation of5 with CH₂N₂ gives6. The¹H-NMR-spectrum of6 makes a definite structural assignment possible.6 undergoes a Dieckmann cyclisation to7, which forms8 on heating in water, and the title compound9 on heating in 4n-HCl.     

Three new Cu(II)-Ln(III) heterometallic coordination polymers constructed from quinolinic acid and nicotinic acid: Synthesis, structures, and magnetic properties

Three new Cu(II)-Ln(III) heterometallic coordination polymers based on two N-heterocyclic carboxylic ligands, {[LnCu(L¹)₂(L²)(H₂O)₂]·mH₂O} _n (Ln = La(1), Nd(2), Gd(3), m = 2 (for 1), 1 (for 2, 3), H₂L¹ = quinolinic acid, HL² = nicotinic acid), have been synthesized and characterized. 1 has a two-dimensional (2D) layer structure with a Schl?fli symbol of (4⁴.6²), while complexes 2 and 3 are isostructural and have three-dimensional (3D) structures with a Schl?fli symbol of (3.4.5)₂(3².4².5².6¹⁴.7⁴.8³.9)(3².6³.7) of 3-nodal net. Magnetic investigations suggest that antiferromagnetic coupling exists between Nd^III and Cu^II in 2, while weak ferromagnetic coupling between Gd^III and Cu^II in 3. The difference of magnetic properties between 2 and 3 has been discussed.     

Darstellung und Struktur von Pyrazolyl-Kationen mit Polymethin- und Methan-Gerüst

The 4-pyrazoline-3-one1 reacts with 4-dimethylaminobenzaldehyde to yield the stable asymmetric cyanine dye2b which reacts with1 to give the colorless (aryl) (dipyrazolyl) methane3b. Using aldehydes with less cationstabilizing groups the polymethines2 are not isolated but only the methanes3. The structures of2b and3 are discussed by¹ H,¹³C and Hetero NMR spectra.     

The electronic structure of 5-methylhexa-1,2,4-triene-1,3-diyl, the first representative of highly delocalized triplet ethynylvinylcarbenes, from ESR spectroscopy data and quantum chemical calculations

The ESR spectrum of the first representative of highly conjugated triplet ethynylvinylcarbenes, 5-methylhexa-1,2,4-triene-1,3-diyl (1), was recorded in solid argon matrix. The zero-field splitting (ZFS) parameters of carbene 1 (D = 0.5054±0.0006 cm^?1 and E = 0.0045±0.0002 cm^?1) determined from the experimental ESR spectrum are in between the corresponding parameters of ethynylcarbene C3H2 (2) and vinylcarbene C₃H₄ (3): D(3) < D(1) < D(2) and E(2) < E(1) < E(3). Quantum chemical calculations of the ZFS parameters of 1, 2, and 3 have been carried out for the first time using two DFT-based approaches, RODFT and UDFT. An analysis of the experimental and theoretical ZFS parameters shows that carbene 1 is characterized by a greater extent of delocalization of the spin density of unpaired electrons than carbenes 2 and 3. The characteristic structural fragments of carbene 1 possess the principal features of the electronic structure of both ethynylcarbene (2) and vinylcarbene (3), respectively. Magnetic spin-spin interactions are identical in carbenes 1 and 2. The dominant contribution to D in 1 and 2 results from the one-center spin-spin interactions on carbon atoms in the propynylidene group, which are subjected to strong spin polarization.     

Comparative investigation of the copper(II) complexes of (R)-, (S)- and (R,S)-1-phenyl-N,N-bis(pyridine-3-ylmethyl)ethanamine along with the related complex of (R,S)-1-cyclohexyl-N,N-bis(pyridine-3-ylmethyl)ethanamine. Synthetic, magnetic, and structural studies

The interaction of the enantiopure (R)- and (S)-1-phenyl-N,N-bis(pyridine-3- ylmethyl)ethanamine ligands, R-L ¹ and S-L ¹ , with copper(II) chloride followed by addition of hexafluorophosphate resulted in the isolation of the corresponding enantiomeric complexes [Cu(R-L ¹ )Cl](PF₆) (1), [Cu(S-L ¹ )Cl](PF₆) (2) and [Cu(S-L ¹ )Cl](PF₆)??0.5Et₂O (3), in which dimerization occurs through two long Cu??????Cl interactions, the ??-chloro bridges being thus strongly asymmetric. The organic ligand is bound to the metal centre via its N₃-donor dipyridylmethylamine fragment in a planar fashion, such that each copper centre is in a square planar environment (or distorted square pyramidal with a long axial bond length if the additional interaction is considered). When R,S-L ¹ was employed in a parallel synthesis, the similar racemic complex [Cu(R,S-L ¹ )Cl](PF₆)??0.5MeOH (4) was obtained, in which the L ¹ ligands in each dimeric unit have opposite hands. In contrast to the complexes of L ¹ , the reaction of Cu(II) chloride with the related ligand, (R)-1-cyclohexyl-N,N-bis(pyridine-3-ylmethyl)ethanamine (R-L ² ), yielded the mononuclear complex [Cu(R,S-L ² )Cl₂] (5), displaying a distorted square pyramidal coordination geometry. The structure of this product along with its corresponding circular dichroism spectrum revealed that racemisation of the starting R-L ² ligand has occurred under the relatively mild (basic) conditions employed for the synthesis. A temperature-dependent magnetic studies of the complexes 1, 2 and 5 indicate that a week ferromagnetic interaction is operative in each dicopper core in 1 and 2 with 2J?=?1.2?cm^?1. On the other hand, a week antiferromagnetic intermolecular interaction is operative for 5.     

Über Reaktionen mit Betainen, 18. Mitt. Über Betaine und ihre Beziehungen zu N-Yliden. Trifluoracetyl-N-methylide und ihre Beziehungen zu den entsprechenden Ammoniumbasen

The betaines1b–d were prepared⁴ by systematic variation of the alkyl groups and were reacted with trifluoroacetic acid anhydride (TFA) to give the diacyl-ylides2b,c. The betain1d andTFA afford the trifluoroacetate3d ⁵. The salts3b,c, which result from hydrolysis of2b,c as well as3d (X=I) can be transformed in 75 to 83% yield into the monoacyl-ylides4b–d with the help of silver oxide. Aqueous solutions of4a–d exhibit alkalinepH, which points to the formation of the corresponding ammonium bases. In the case of4b,c the bases5b,c could be isolated. It can be shown, that4b,c and5b,c, respectively, undergo a reversible addition or elimination of one mole wather with great ease.     

Silica-immobilized N,O-prolinate ruthenium benzylidene complexes for catalytic applications

The immobilization of N,O-prolinate ruthenium benzylidene complexes as hybrid silicas is reported according to three routes: (i) co-condensation of a silylated precursor, 10, with TEOS via the sol–gel process (material M1); (ii) grafting of the same precursor on a preformed mesoporous silica M2 (material M3); entrapment of a parent non-silylated compound, 8, in the preformed mesoporous silica M2 (material M4). They have been characterized by several techniques. Solid state ²⁹Si NMR measurements ensure the anchorage of the Ru-complexed prolinate fragment in the silica matrix of M1 and M3 by the presence of T and Q sites, while only Q sites are observed as expected for M4. Elemental analyses provide the N/Si ratios and TGA experiments give the weight loss of the organics during decomposition and hence indicating the amount of organics inserted in the materials. Adsorption–desorption analyses show that these solids had surface areas ranging from 310 to 620 m²g^?1.These materials were tested as solid catalysts for two different reactions: ring-closing olefin metathesis and hydrosilylation of phenylacetylene with HSiEt₃. Their recyclability has also been investigated. While M1 is the less active for the first reaction giving low conversions and selectivity compared to M3 and M4, it is by far the most efficient catalyst for the second reaction.     

Über die Synthese von 1,3-Dihydro-3-(2-dimethylaminoäthyl)-1-(3-thienyl)-benzimidazol-2-onen

The synthesis of 1-(3-thienyl)-benzimidazol-2-ones (3 a and4), described in an earlier paper¹, has been further investigated. The Na-salt of3 a is converted to a benzimidazolone substituted in position 3 (3 b). Dehydrogenation of the thiophene nucleus of3 a with chloranil yields5 a, which undergoes substitution in position 3 with Cl(CH₂)₂N(CH₃)₂ to give5 b. Monochlorination of5 a yields5 c, the structure of which is confirmed by¹H-NMR-spectroscopy.5 d is obtained by reaction of the Na-salt of5 c with Cl(CH₂)₂N(CH₃)₂.      

Mono- and diprotonation of dihydropyrene, 2,7-di-tert-butyl-dihydropyrene,and their conversion to pyrenium ions; Influence of the radical cation and its potential utility in NMR assignments of the arenium ions of readily oxidizable PAHs

Parent dihydropyrene 1 and 2,7-di-tert-butyldihydropyrene 3 are monoprotonated with FSO₃H/SO₂CIF to give their persistent monoarenium ions 1H ⁺ and 3H ⁺ by the attack of proton at C-3 (peri to the ethano-bridge not at C-1 as previously suggested). Dihydropyrene 3 is diprotonated in FSO₃H.SbF₅ 1∶1 “Magic Acid”^R/SO₂CIF to give the symmetrical dication 3H ₂ ⁺², similar diprotonation of 1 with “Magic Acid”/SO₂CIF or with FSO₃H.SbF₅ (4∶1)/SO₂CIF gave the diprotonated species 1H ₂ ⁺² in a mixture. NMR characteristics of the mono- and dications are discussed. On raising temperature or on prolonged cold storage, 1H ⁺ and 3H ⁺ are converted to their corresponding pyrenium cations (2H ⁺ and 4H ⁺). Formation of 2H ⁺ from 1 is more rapid than conversion of 3 to 4H ⁺. Parent pyrenium cation was independently generated by protonation with FSO₃H/SO₂CIF. When a mixture of 2 and 1 is reacted with FSO₃H/SO₂CIF (dry ice/acetone temperature) only 2H ⁺ is seen in the NMR (concomitant presence of the radical cation 1 ⁺⁺ is inferred from EPR). Similar protonation of a mixture of 6-chlorochrysene 5 and 1 with FSO₃H/SO₂CIF leads to NMR observation of 1H ⁺ (with concomitant presence of 5 ⁺⁺); on raising temperature 1H ⁺ is converted to 2H ⁺. The nature of the paramagnetic radical cation (RC) present in the arenium ion samples influences the position, and resolution of the NMR spectra. This approach may prove useful in NMR studies of large polycyclic aromatic hydrocarbons PAHs where concomitant RC formation greatly diminishes the quality of the NMR spectra.     

Anion-directed organized assemblies of protonated pyrazole-based ionic salts

The reactions of 3(5)-(4-methoxyphenyl)-5(3)-phenyl-1H-pyrazole (L ¹ ) with nitric acid and 5-(4-benzyloxyphenyl)-3-(furan-2-yl)-1H-pyrazole(L ² ) with hydrochloric acid produced [HL ¹ · NO₃] (Salt-1) and [HL ² · Cl] (Salt-2). The structures of Salt-1 and Salt-2 were determined by single crystal X-diffraction. In Salt-1, HL ¹ showed [2 + 2] binding of NO₃ ^? ions in the solid state to form dimer architecture with R ₁ ² (4) and R ₄ ⁴ (14) graph sets. An anion directed one-dimensional anion-assisted helical chain with active participation of the chloride ion and protonated pyrazole via N–H···Cl hydrogen bonding in Salt-2. In addition, the protonated HL ² molecules interacted with each other through weak C–H···π interactions resulting in the formation of another one-dimensional helical chain.     

Di- and tetranuclear heterometallic CuII-LnIII complexes (Ln = Gd and Dy): Synthesis, structure and magnetic properties

Four 3d-4f heterometallic complexes, [CuⅡ LnⅢ (bpt) 2 (NO 3 ) 3 (MeOH)] (Ln = Gd, 1; Dy, 2; bptH = 3,5-bis(pyrid-2-yl)-1,2,4- triazole), [CuⅡ 2 LnⅢ 2 (μ-OH) 2 (bpt) 4 Cl 4 (H 2 O) 2 ]·6H 2 O (Ln = Gd, 3; Dy, 4), have been synthesized under solvothermal conditions. X-ray structural analyses reveal that 1 and 2 are isostructural while 3 and 4 are isostructural. In each complex, the copper and gadolinium or dysprosium ions are linked by two triazolate bridges and form a CuⅡ -LnⅢ dinuclear unit. The intramolecular Cu-Ln distances are 4.542, 4.525, 4.545 and 4.538 for 1, 2, 3 and 4, respectively. Two dinuclear CuLn units are bridged by two OH- groups into the zig-zag tetranuclear {CuⅡ 2 LnⅢ 2 } structures with the Ln(Ⅲ) Ln(Ⅲ) distances of 3.742 and 3.684 for 3 and 4, respectively. Magnetic studies show that the antiferromagnetic CuⅡ-LnⅢ interactions occur in 1 (J CuGd = 0.21 cm-1 ) and 2. The antiferromagnetic interaction occurs in complex 3 with J CuGd = 0.82 cm-1 and J GdGd = 0.065 cm-1 , while dominant ferromagnetic interaction occurs in complex 4.     

Spectroscopic studies of charge-transfer complexation of iodine with a new benzo-substituted macrocyclic diamide in chloroform, dichloromethane and their 1:1 mixture

Charge-transfer complexation of iodine with a new benzo-substituted macrocyclic diamide 5,6,7,8,9,10-hexahydro-2H-1,13,4,7,10-benzodioxatriazacyclopentadecine-3,11(4H,12H)-dione (L) with iodine was studied spectrophotometrically in chloroform, dichloromethane and their 1:1 (v/v) mixture. The observed time dependence of the charge-transfer band and subsequent formation of I₃ ^- ion are related to the slow formation of the initially formed 1:1 L.I₂ outer complex to an inner electron donor-acceptor (EDA) complex, followed by fast reaction of the inner complex with iodine to form a triiodide ion, as follows: L + I₂ → L.I₂ (outer complex), fast L.I₂ (outer complex) → (L.I⁺)I^- (inner complex), slow (L.I⁺)I^- (inner complex) + I₂ → (L.I⁺)I₃ ^-, fast The pseudo-first-order rate constants for the transformation process were evaluated in different solvent systems. The stability constants of the resulting EDAr complexes were also evaluated and the solvent effect on their stability is discussed. The resulting complexes were isolated and characterized by FTIR and ¹H NMR spectroscopy.     

Über die Reaktionen von monosubstituierten Guanidinen mit 1-Phenyl-1,3-butandion

Methyl-, benzyl- and phenylguanidine (2 b–d) react with 1-phenyl-1,3-butanedione to yield exclusively N²-substituted 4-methyl-6-phenyl-2-pyrimidinamines10 b–d. The formation of isomeric N¹-substituted 2(1H)-pyrimidinimines11 or12 cannot be observed. The structural formulae of10 b and c were proved by spectroscopical methods. The structure of the phenylguanidine-phenylbutanedione-condensate was determined by comparison and establishment of the identity of its picrate with an authentical sample of10 d-picrate, which had been synthetized from pyrimidinthione13 (via methylthiopyrimidine16 · HI). Boiling13 with aniline in butanol yields thiodipyrimidine15 (and not10 d).     

Prepatellamide A, a new cyclic peptide from the ascidianLissoclinum patella

A new cyclic peptide, prepatellamide A (1), along with three known cyclic peptides (2)— (4), was isolated from the ascidianLissoclinum patella. The structure of prepatellamide A was determined from one- and two-dimensional¹H and¹³C NMR spectra. The known cyclic peptides were identified as patellamides A (2), B (3) and C (4).     

Synthesis and cation complexation of calix[4]azacrowns and a spirobiscalix[4]azacrown

The synthesis and complexation properties of three new derivatives, one spirobiscalix[4]azacrown (1) and two calix[4]azacrown (2 and 3), are reported. Complexation studies of the three ligands toward transition and heavy metal cations have been carried out and monitored by UV absorption spectrophotometry in acetonitrile. Mononuclear complexes were detected for all complexes, whereas binuclear species (M₂L) were also formed in the case of ligand 1 with Cu²⁺ and Pb²⁺. The extraction properties of 1, 2 and 3 toward Cu²⁺, Zn²⁺, Pb²⁺, Ag²⁺ and Cd²⁺ are also reported. The results showed that complexation is the main factor affecting extraction with ligands 2 and 3, while with ligand 1 it is not.     

3,6-Dialkyl-1-phenyl-6-phenylazo-1,4,5,6-tetrahydropyridazine, (4+2)-Cycloadditionsprodukte aus 2-Phenylazo-1-alkenen, 1. Teil: Synthese und spektroskopische Strukturermittlungen

The 2-phenylazo-1-alkenes1a-e are not isolable as pure compounds. They dimerize in a regioselective (4+2)-cycloaddition to orange yellow 3.6-dialkyl-1-phenyl-6-phenylazo-1.4.5.6-tetrahydropyridazines2a-e. The structure of these cyclodimers2a-e as well as of a cross product (2f) has been proved by spectroscopic methods (ir and Raman, uv,¹H-nmr, ms).     

Pyrindinchemie, 1. Mitt.: Über die Synthese des 3-Hydroxy-1-methyl-4-oxo-1,4-dihydropyrrolo[2′,3′:3,4]cyclopenta[1,2—b]pyridin-2-carbonsäureäthylesters (Ein Vertreter eines neuen heterocyclischen Ringsystems)

4 is synthesized starting from1 over the chloride3 and then cyclized byDieckmann condensation to the title compound8. The structure of4 is confirmed by chemical proof. By means of¹H-NMR-spectral analysis it could be determined that1 exists as internal salt (2a) of ethyl 5-hydroxy-7-oxo-7H-1-pyrindin-6-carboxylate.     

Syntheses, spectroscopic characterization and metal ion binding properties of benzo-15-crown-5 derivatives and their sodium and nickel(II) complexes

New benzo-15-crown-5 derivatives containing nitro, amine and imine groups were prepared. Nitro compound (1) was prepared after the reaction?4′,5′-bis(bromethyl)benzo-15-crown-5 and o-nitrophenol in the presence of NaOH. After reduction process by using hydrazine hydrate and Pd/C amine compound (2) was formed. New crown ether imine compounds (3–5) were synthesized by the condensation of corresponding crown ether diamine (2) with salicylaldehyde derivatives. Sodium complexes of the crown compounds (1a–5a) form crystalline 1:1 (Na⁺: ligand) complexes with sodium perchlorate. Nickel(II) complexes (3b–5b) with 1:1 (Ni²⁺:ligand) stoichiometries were also been synthesized from the Schiff bases (3–5). The results indicated that the Schiff base ligands coordinated through the azomethine nitrogen and phenolic oxygen. The extraction ability of compounds (1, 3, 4 and 5) were also evaluated in chloroform by using several alkali and transition metal picrates such as Li⁺, Na⁺, K⁺, Cr³⁺, Mn²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Pb²⁺.     

Synthese,Kristallstruktur und Konformation vontrans-[2.2](1,2)Ferrocenophan und seinen 1-Hydroxyderivaten

Starting from1-(dimethylaminomethyl)-2-iodo-ferrocene (3) [2.2](1,2)ferrocenophane (2) was prepared in an 8-step synthesis with 17% overall yield. Both from the oxoderivative12 and the ferrocenophane2 puretrans-isomers (12b and2b, resp.) were obtained; the former (12b) was reduced to a separable mixture ofexo andendo 1-hydroxy-ferrocenophanes13a andb, resp. (～ 3:7), the configurations of which were assigned by the LIS-method. X-ray crystal structure analysis of2b revealed a centrosymmetrical chair conformation. From¹H- and¹³C-NMR spectra both for2b and for the hydroxyderivatives13 a rigidexo-exo chair conformation was deduced.