Synthesis, characterization and crystal structures of boron-containing intermediates in the reductive amination of ferrocenecarboxaldehyde to a bis(ferrocenylmethyl) amine

Reaction of ferrocenecarboxaldehyde with aqueous methylamine leads to [(methylimino)methyl]ferrocene, which is reduced to N-(ferrocenylmethyl)-N-methylamine by NaBH₄. This amine reacts with ferrocenecarboxaldehyde and NaCNBH₃ to give the tertiary ammonium salt, di(N-(ferrocenylmethyl))-N-methylammonium cyanoborohydride. Hydrolysis of the NaCNBH₃ reaction mixture produces the free amine, di(N-(ferrocenylmethyl))-N-methylamine. Thermolysis of di(N-(ferrocenylmethyl))-N-methylammonium cyanoborohydride in refluxing tetrahydrofuran converts it to the cyanoborane adduct, di(N-ferrocenylmethyl)-N-methylamine-cyanoborane, with elimination of H₂. The new compounds are fully characterized by using spectroscopic and physical methods, including X-ray crystal structure determinations of di(N-(ferrocenylmethyl))-N-methylammonium cyanoborohydride, di(N-(ferrocenylmethyl))-N-methylamine, and di(N-(ferrocenylmethyl))-N-methylamine-cyanoborane.     

Mechanism study on the reactions between biphenyl and HNO_2 initiated by 355 nm irradiation in aqueous phase

The reactions taking place in the mixed solution of biphenyl and nitrous acid after it was exposed to UV irradiation were studied in this research work. The transient species were identified with the nanosec- ond transient spectroscopic technique, and the final products were ascertained by GC-MS analysis. It was shown that the OH radical, generated by the direct photolysis of nitrous acid, would attack biphe- nyl molecule to form Bp-OH adduct with a rate constant of 9.5×109 L·mol?1·s?1. The Bp-OH adduct could either react with H or be oxidized by nitrous acid to form nitrosobiphenol. The reactions between biphenyl and nitrous acid under UV irradiation in atmospheric aqueous phase were therefore sug- gested to be one promising source of nitrocompounds in the environment.     

Triplet excited states and radical intermediates formed in electron pulse radiolysis of amino-substituted fluorenones

Electron pulse radiolysis of four differently substituted amino derivatives of fluorenone, namely, 1-amino-, 2-amino- 3-amino-, and 4-aminofluorenone, has been carried out to study the effect of structure on the spectroscopic and kinetic characteristics of the triplet excited states as well as the transient free radical intermediates formed under reducing and oxidizing conditions. The triplet states of these compounds have been generated in benzene by pulse radiolysis and in other solvents by flash photolysis technique and their spectral and kinetic properties have been investigated. Hydrated electron (e_aq⁻) has been found to react with these fluorenone derivatives to form the anion radical species with a diffusion-controlled rate constant. The spectral and kinetic properties of the transient ketyl and anion radicals have been studied by generating them in aqueous solutions of suitable pH. The pK_a values of ketylanion radical equilibria are in the range of 6.8–7.7 for these derivatives. The oxidized species have been generated by reaction with the azide radical. Hydrogen atom adducts as well as the cation radicals of these derivatives have also been generated by pulse radiolysis and characterized.     

CRYSTAL STRUCTURE OF THE ADDUCT OF DECAVANADATE AND HEXAMETHYLENE-TETRAMINE {[HMT· H~+(V_(10)O_(28))~(6-)·H~+·HMT]· 2[HMT· CH_2NH_2]~+·2(H_3~+O)·12H~2O}

The title compound crystal belongs to the trilinic space group C_i~1—P(?) with unit cell parameters: a=11.208 (4), b=13.166 (4), c=13.239 (3),α=118.15 (2)°,β=94.78(2)°,γ=109.19 (2)°, and Z=1. The crystal structure was solved by direct method and difference Fourier techniques using the SHELXTL program, and was refined finally to R=R_W=0.0462 for 4702 reflections. Structural analysis shows that the four protons in the cluster of the decavanadate group are separated into two types. For one of them, the two protons are captured by two O7 in the cluster of the decavanadate and two nitrogen atoms of the hexamethylenetetramine, to form hydrogen bonds; moreover, we have verified that the N-aminomethylhexamethylenetetraminium which was produced during the reaction existed in the title compound crystal. We infer that the N-aminomethylhexamethylenetetraminium [(CH_2)_6N_4CH_2NH_2]~+ could be produced by the heterogeneous catalysis reaction from the surface of the vanadium pentoxide [V_2O_5].     

A comparative solvent extraction study of manganese(II) with 8-Mercaptoquinoline, 8-Quinolinol and its analogues

Equilibrium distribution coefficients were determined for the extraction of manganese(II) with 8-mercaptoquinoline, 8-quinolinol and its 2-methyl, 4-methyl, 5-chloro and 5-nitro analogues as a function of pH and reagent concentration at ambient temperature. 8-Mercaptoquinoline forms a mono self-adduct with Mn(II) whereas simple 12 chelate formation was observed in the case of 8-quinolines. The adduct formation constant and the overall formations constants in the aqueous phase have been determined. A linear relationship was observed between the equilibrium constants, formation constants and the pK values of the chelating agents.Synergic enhancement was observed in the extraction of Mn(II) with 8-mercaptoquinoline in presence of pyridine and its methyl derivatives and the adduct formation constants of the 12, chelate to nitrogen base, adducts were evaluated.     

New approach to the functionalization of δ-carboline derivatives

The possibility of transformation of 3-cyano-1-p-nitrophenyl--carbolin-2-one into 2-amino-3-cyano-1-p-nitrophenyl-1H-pyrido[3,2-b]indole derivatives and 2-imino-3-cyano-1-p-nitrophenyl-5H-pyrido[3,2-b]indole derivatives (-carbolines) is demonstrated. Methylation of 1-p-nitrophenyl-2-piperidino-1H--carboline followed by treatment with acetone in an alkaline medium yields 4-acetonyl-5-methyl-1,4-dihydro-5H-pyrido[3,2-b]indole derivative. The rearrangement of 2-arylimino-3-cyano-1-p-nitrophenyl-5H-pyrido[3,2-b]indoles into 2-(aryl)nitrophenylamino-3-cyano-5H-pyrido[3,2-b]indoles was accomplished on heating above the melting point or on treatment with potassium tert-butoxide. The structures of the resulting compounds were proved by ¹H and ¹³C NMR spectroscopy and X-ray diffraction analysis.     

Synthesis and Crystal Structure of Macrocyclic Cavitand Cu-curbit[5]uril and Its Supramolecular Adduct with Cu(II)

Introduction The cucurbit[n]urils (CB[n]s) are a kind of cyclic methylene-linked glycoluril oligomers and possess a characteristic annular shape, with two identical car-bonyl-fringed portals.1-3 As the most common cucurbi-turil, CB[6], has been widely studied in supramolecular chemistry by the groups of Mock4 and Kim.5 Recently, other CB[n] (n=5, 7, 8), the molecular recognition properties of which are different from those of CB[6] itself, have been extensively utilized in molecular rec-og…     

A facile one-pot stereoselective synthesis of trisubstituted (E)-2-methylalk-2-enoic acids from unactivated Baylis-Hillman adducts and a simple access to some important insect pheromones

An efficient one-pot stereoselective synthesis of trisubstituted (E)-2-methylalk-2-enoic acids has been accomplished by treatment of unactivated Baylis-Hillman adducts, 3-hydroxy-2-methylenealkanoates, with Al-NiCl₂·6H₂O in methanol at room temperature followed by hydrolysis. The method has been applied to the synthesis of three important insect pheromones, (4S,2E)-2,4-dimethyl-2-hexenoic acid, (+)-(S)-manicone and (+)-(S)-normanicone.     

Reactions of 2-(perfluoroalkyl)ethane thiols with 1,6-heptadiene and 4-substituted 1,6-heptadienes: the synthesis of RFethanethio-cyclopentanoic and -dioic acids; and, “geminal-twin-tail” bis-(perfluoroalkylethanethio)alkanoic acids

Kinetic analysis of the free radical addition of n-C₆F₁₃I to 1,6-heptadiene gives a rate ratio of cyclization to addition (k_d1/k_c) of 0.568 at 70 °C; thus, the rate of cyclization (k_c) is twice that of iodine transfer (k_d1). By contrast, for n-C₆F₁₃CH₂CH₂SH (k_d1/k_c) = 14.4 at 70 °C, and radical transfer of H from the thiol is 14.4 times the faster than cyclization. Substitution at the center of 1,6-heptadiene has a profound effect on the linear/cyclic adduct ratio. For the addition of n-C₃F₇I (R_FI:diene=2:0) the adduct ratios dramatically decrease in the order: 1,6-heptadiene (1.17) > 4-carboxy-1,6-heptadiene (0.0613) > 4,4-bis-ethoxycarbonyl-1,6-heptadiene (<0.001). Bis-addition to the 4,4-substituted dienes is strongly disfavored, and the desired “geminal-twin-tail” [R_F(CH₂)₃]₂CHCO₂R, or [R_F(CH₂)₃]₂C(CO₂R)₂ must be synthesized by other means. For the reaction of R_FCH₂CH₂SH with the dienes (1:1), the respective adduct ratios are 11.3 (n-C₆F₁₃), 0.370 (n-C₈F₁₇), and 0.0716 (n-C₆F₁₃). However, adding the 4-carboxy-1,6-heptadiene slowly to four mols of n-C₈F₁₇CH₂CH₂SH yields 98% of the geminal bis-adduct [R_FCH₂CH₂S(CH₂)₃]₂CHCO₂H, which is a new, fluorophilic, geminal-twin-tail acid.     

Dimethylzinndithioquadratat: Die Kristallstruktur des Benzol-Solvats und des Dimethylsulfoxid-Addukts

Dimethyltin Dithiosquarate: The Crystal Structure of the Benzene Solvate and of the Dimethylsulfoxide Adduct (CH₃)₂SnS₂C₄O₂ · 1/3 C₆H₆ ( I ) crystallizes in the orthorhombic space group Pnma. a = 14.393(2), b = 21.668(3), c = 10.424(1) Å, Z = 12. (CH₃)₂SnS₂C₄O₂ · (CH₃)₂SO ( II ) is monoclinic, space group P2₁/n, a = 9.918(5), b = 12.028(6), c = 12.223(6) Å, β = 108.82(3)°, Z = 4. In I there are two independent dimethyltin dithiosquarate molecules. But in both molecules the Sn atoms display weak coordinative bonds to two O atoms of adjacent dithiosquarate groups. The distances amount 2.873 Å (2×), resp. 2.678 and 2.831 Å. The coordination number of tin becomes 6 and the structure gets connected in three dimensions. In II dimethylsulfoxide is bound with the O atom to Sn (2.345 Å) and the result is a distorted trigonal bipyramid. There a more distant O atom (2.944 Å) leads to a connection of the molecules to a ribbon. The changes of the geometrical parameters are described, which result from the progressive approach of the one O atom.