Simultaneous determination of stable isotopically labelled L-histidine and urocanic acid in human plasma by stable isotope dilution mass spectrometry.

A capillary gas chromatographic-mass spectrometric method for the simultaneous determination of stable isotopically labelled L-histidine (L-[3,3-2H2,1',3'-15N2]histidine, L-His-[M + 4]) and urocanic acid ([3-2H,1',3'-15N2]urocanic acid, UA-[M + 3]) in human plasma was developed using DL-[2,3,3,5'-2H4,2'-13C,1',3'-15N2]histidine (DL-His-[M + 7]) and [2,3,5'-2H3,2'-13C,1',3'-15N2]urocanic acid (UA-[M + 6]) as internal standards. L-Histidine and urocanic acid were derivatized to alpha N-(trifluoroacetyl)-imN-(ethoxycarbonyl)-L-histidine n-butyl ester and imN-(ethoxycarbonyl)urocanic acid n-butyl ester. Quantification was carried out by selected ion monitoring of the molecular ions of the respective derivatives of L-His-[M + 4], DL-His-[M + 7], UA-[M + 3] and UA-[M + 6]. The sensitivity, specificity, precision and accuracy of the method were demonstrated to be satisfactory for measuring plasma concentrations of L-His-[M + 4] and UA-[M + 3] following administration of trace amounts of L-His-[M + 4] to humans.     

Controlled Double-Bond Migration in Palladium-Catalyzed Intramolecular Arylation of Enamidines

Palladium-catalyzed intramolecular cyclization of N-(N'-tert-butylformimidoyl)-6-[2-(2-iodophenyl)ethyl]-1,2,3,4-tetrahydropyridine (1a) and N-(N'-tert-butylformimidoyl)-6-[3-(2-iodophenyl)propyl]-1,2,3,4-tetrahydropyridine (1b) respectively results in formation of spiro compounds 1'-(N-tert-butylformimidoyl)-3',4'-dihydrospiro[indan-1,2'(1'H)-pyridine] (4a), 1'-(N-tert-butylformimidoyl)-1',6'-dihydrospiro[indan-1,2'(3'H)-pyridine] (5a), and 1'-(N-tert-butylformimidoyl)-5',6'-dihydrospiro[indan-1,2'(1'H)-pyridine] (6a) and 1'-(N-tert-butylformimidoyl)-3,3',4,4'-tetrahydrospiro[naphthalene-1(2H),2'(1'H)-pyridine] (4b), 1'-(N-tert-butylformimidoyl)-1',3,4,6'-tetrahydrospiro[naphthalene-1(2H),2'(3'H)-pyridine] (5b), and 1'-(N-tert-butylformimidoyl)-3,4,5',6'-tetrahydrospiro[naphthalene-1(2H),2'(1'H)-pyridine] (6b). The double-bond migration process can be controlled, and any of the three double-bond isomers can be prepared by employing proper ligands. A combination of BINAP and the amidine function was required to obtain the isomers 5a and 5b with the double bond in the homoallylic position relative to the aryl group. An electrospray ionization mass spectrometric study was conducted to support suggested reaction intermediates.     

Improved preparation of (1S,3’R,4’S,5’S,6’R)-5-chloro-6-[(4-ethylphenyl)methyl]-3’,4’,5’,6’-tetrahydro-6’-(hydroxymethyl)-spiro[isobenzofuran-1(3H),2’-[2H]pyran]-3’,4’,5’-triol

A convenient approach for the preparation of(1S,3’R.4’S,5’S,6’R)-5-chloro-6-[(4-ethylphenyl)methyl]- 3’,4’,5’,6’-tetrahydro-6’-(hydroxymethyl)-spiro[isobenzofuran-1(3H),2’-[2H]pyran]-3’,4’,5’-triol is developed. The targeted compound was synthesized from 2-bromo-4-methylbenzoic acid in nine steps and the isomers of undesired ortho-products were avoided during the preparation.     

Transition-state analysis of S. pneumoniae 5'-methylthioadenosine nucleosidase

Kinetic isotope effects (KIEs) and computer modeling are used to approximate the transition state of S. pneumoniae 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN). Experimental KIEs were measured and corrected for a small forward commitment factor. Intrinsic KIEs were obtained for [1'-3H], [1'-14C], [2'-3H], [4'-3H], [5'-3H(2)], [9-15N] and [Me-3H(3)] MTAs. The intrinsic KIEs suggest an SN1 transition state with no covalent participation of the adenine or the water nucleophile. The transition state was modeled as a stable ribooxacarbenium ion intermediate and was constrained to fit the intrinsic KIEs. The isotope effects predicted a 3-endo conformation for the ribosyl oxacarbenium-ion corresponding to H1'-C1'-C2'-H2' dihedral angle of 70 degrees. Ab initio Hartree-Fock and DFT calculations were performed to study the effect of polarization of ribosyl hydroxyls, torsional angles, and the effect of base orientation on isotope effects. Calculations suggest that the 4'-3H KIE arises from hyperconjugation between the lonepair (n(p)) of O4' and the sigma* (C4'-H4') antibonding orbital owing to polarization of the 3'-hydroxyl by Glu174. A [methyl-3H(3)] KIE is due to hyperconjugation between np of sulfur and sigma* of methyl C-H bonds. The van der Waal contacts increase the 1'-3H KIE because of induced dipole-dipole interactions. The 1'-3H KIE is also influenced by the torsion angles of adjacent atoms and by polarization of the 2'-hydroxyl. Changing the virtual solvent (dielectric constant) does not influence the isotope effects. Unlike most N-ribosyltransferases, N7 of the leaving group adenine is not protonated at the transition state of S. pneumoniae MTAN. This feature differentiates the S. pneumoniae and E. coli transition states and explains the 10(3)-fold decrease in the catalytic efficiency of S. pneumoniae MTAN relative to that from E. coli.     

Synthesis of polyphenylene dendrimers related to "cubic graphite"

Four large, 6-fold symmetric, polyphenylene hydrocarbons have been prepared by short syntheses that chiefly employed alkyne trimerization, palladium-catalyzed coupling, and Diels-Alder reactions. The two largest of these molecules, hexakis[4'-(pentaphenylphenyl)biphenyl-4-yl]benzene (4, C(294)H(198)) and hexakis[4'-(2,3,4,5-tetraphenylphenyl)biphenyl-4-yl]benzene (5, C(258)H(174)) are substructures of "phenylogous cubic graphite", and the other two, hexakis(2',3',4',5',6'-pentaphenylbiphenyl-4-yl)benzene (26, C(258)H(174)) and hexakis(2',3',4',5'-tetraphenylbiphenyl-4-yl)benzene (25, C(222)H(150)) are strongly pitched, six-bladed molecular propellers. The X-ray crystal structure of compound 26 has also been determined; dendrimer 26 is at present the largest crystallographically characterized hydrocarbon.     

Solution self-assembly, spontaneous deprotonation, and crystal structures of bipyrazolate-bridged metallomacrocycles with dimetal centers

A series of nanosized cavity-containing bipyrazolate-bridged metallomacrocycles with dimetal centers, namely, {[(bpy)M]8L4}(NO3)8 [L=3,3',5,5'-tetramethyl-4,4'-bipyrazolyl, Pd, Pt; 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene), Pd; and 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbiphenyl, Pd], {[(phen)M]8L4}(NO3)8 [L=3,3',5,5'-tetramethyl-4,4'-bipyrazolyl, Pd, Pt; 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, Pd; and 1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbiphenyl, Pd], {[(bpy)Pd]6L3}(NO3)6 [L=1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], {[(phen)Pd]6L3}(NO3)6 [L=1,4-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], {[(bpy)Pd]4L2}(NO3)4 [L=1,3-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, and 1,2-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,], and {[(phen)Pd]4L2}(NO3)4 [L=1,3-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene, and 1,2-bis-4'-(3',5'-dimethyl)-pyrazolylbenzene,] (where bpy=2,2'-bipyridine and phen=1,10-phenanthroline) have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the 1H-bipyrazolyl ligands in aqueous solution. These complexes, with weak Pd(II)...Pd(II) or Pt(II)...Pt(II) interactions, have been characterized by elemental analysis, 1H and 13C NMR, cold-spray ionization or electrospray ionization mass spectrometry, UV-visible spectroscopy, and luminescence spectroscopy. Complexes and have also been characterized by single-crystal X-ray diffraction analysis.     

2'-hydroxypyridoxol, a biosynthetic precursor of vitamins B(6) and B(1) in yeast

In separate experiments cultures of the yeast Saccharomyces cerevisiae ATTC 7752 were grown in the presence of [5',5'-2H2]- or of [2',2',5',5'-2H4]-3-hydroxy-2,4,5-tri(hydroxymethyl)pyridine (i.e., 2'-hydroxypyridoxol). The 2H NMR spectra of the samples of pyridoxamine dihydrochloride and of thiamin chloride hydrochloride that were isolated from the two experiments showed the presence of deuterium at the corresponding sites. Entry of deuterium from the specifically 2H-labeled samples of 2'-hydroxypyridoxol into the predicted sites of pyridoxamine and of the pyrimidine unit of thiamin provides the first unequivocal evidence that, in yeast, 2'-hydroxypyridoxol is an intermediate on the route from a C5-sugar into vitamin B6, and adds to the evidence that pyridoxol serves as a precursor of the pyrimidine unit of thiamin, supplying the C5N unit, C-2',2,N-1,C-6,5,5' as an intact unit.     

Total synthesis of 2',3',4',5',5' '-(2)h(5)-ribonucleosides: the key building blocks for NMR structure elucidation of large RNA

The diastereospecific chemical syntheses of uridine-2',3',4',5',5' '-(2)H(5) (21a), adenosine-2',3',4',5',5' '-(2)H(5) (21b), cytidine-2',3',4',5',5' '-(2)H(5)(2)H(5) (21c), and guanosine-2',3',4',5',5' '-(2)H(5) (21d) (>97 atom % (2)H at C2', C3', C4', and C5'/C5' ') have been achieved for their use in the solution NMR structure determination of oligo-RNA by the Uppsala "NMR-window" concept (refs 4a-c, 5a, 6), in which a small (1)H segment is NMR-visible, while the rest is made NMR-invisible by incorporation of the deuterated blocks 21a-d. The deuterated ribonucleosides 21a-d have been prepared by the condensation of appropriately protected aglycone with 1-O-acetyl-2,3,5-tri-O-(4-toluoyl)-alpha/beta-D-ribofuranose-2,3,4,5,5'-(2)H(5) (19), which has been obtained via diastereospecific deuterium incorporation at the C2 center of appropriate D-ribose-(2)H(4) derivatives either through an oxidation-reduction-inversion sequence or a one-step deuterium-proton exchange in high overall yield (44% and 24%, respectively).     

Water-soluble [2.2]paracyclophane chromophores with large two-photon action cross sections

A series of alpha,omega-donor-substituted distyrylbenzene dimers held together by the [2.2]paracyclophane core were designed, synthesized, and characterized. Different substituents were chosen to modulate the strength of the donor nitrogen groups and to allow the molecules to be either neutral and soluble in nonpolar organic solvents or charged and water-soluble. The specific neutral structures are (in order of decreasing donor strength) 4,7,12,15-tetra[N,N-bis(6' '-chlorohexyl)-4'-aminostyryl]-[2.2]paracyclophane (1N), 4,7,12,15-tetra[(N-(6' '-chlorohexyl)carbazol-3'-yl)vinyl]-[2.2]paracyclophane (2N), and 4,7,12,15-tetra[N,N-bis(4' '-(6' '-chlorohexyl)phenyl)-4'-aminostyryl]-[2.2]paracyclophane (3N). The charged species are 4,7,12,15-tetra[N,N-bis(6' '-(N,N,N-trimethylammonium)hexyl)-4'-aminostyryl]-[2.2]paracyclophane octaiodide (1C), 4,7,12,15-tetra[(N-(6' '-(N,N,N-trimethylammonium)hexyl)carbazol-3'-yl)vinyl]-[2.2]paracyclophane octaiodide (2C), and 4,7,12,15-tetra[N,N-bis(4' '-(6' '-(N,N,N-trimethylammonium)hexyl)phenyl)-4'-aminostyryl]-[2.2]paracyclophane octaiodide (3C). Two-photon excitation spectra, measured using the two-photon induced fluorescence technique, show in toluene the following trend for the two-photon cross sections (delta): 3N > 2N > 1N. In water the delta values follow the same order, 3C approximately 2C > 1C, but are smaller (approximately one-third). Significantly, the fluorescence quantum yield (eta) in water decreases much more for 1, relative to 2 and 3. The two-photon action cross sections (deltaeta) of 2C and 3C are 294 GM and 359 GM, respectively. These values are among the highest reported thus far. These results show that, to maximize the deltaeta in this class of chromophores, one needs to fine-tune the magnitude of the charge transfer character of the excited state, to minimize fluorescence quenching in polar media.     

Extreme electronic modulation of the cofacial porphyrin structural motif

The synthesis, electrochemistry, and optical spectroscopy of an extensive series of cofacial bis[(porphinato)zinc(II)] compounds are reported. These species were synthesized using sequential palladium-catalyzed cross-coupling and cobalt-mediated [2+2+2] cycloaddition reactions. This modular methodology enables facile control of the nature of macrocycle-to-macrocycle connectivity and allows unprecedented modulation of the redox properties of face-to-face porphyrin species. We report the synthesis of 5,6-bis[(5',5'-10',20'-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (1), 5,6-bis[(2'-5',10',15',20'-tetraphenylporphinato)zinc(II)]indane (2), 5-([2'-5',10',15',20'-tetraphenylporphinato]zinc(II))-6-[(5"-10',20'-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (3), 5-([2'-5',10',15',20'-tetrakis(trifluoromethyl)porphinato]zinc(II))-6-[(5' '-10' ',20' '-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (4), 5-(2'-5',10',15',20'-[tetrakis(trifluoromethyl)porphinato]zinc(II))-6-[(2'-5',10',15',20'-tetraphenylporphinato)zinc(II)]indane (5), 5,6-bis([2'-5',15'-diphenyl-10',20'-(trifluoromethyl)porphinato]zinc(II))indane (6), and 5,6-bis([2'-5',10',15',20'-tetrakis(trifluoromethyl)porphinato]zinc(II))indane (7); 4-7 define the first examples of cofacial bis[(porphinato)metal] compounds in which sigma-electron-withdrawing perfluoroalkyl groups serve as macrocycle substituents, while 2, 6, and 7 constitute the first such structures that possess a beta-to-beta linkage topology. Cyclic voltammetric studies show that the electrochemically determined HOMO and LUMO energy levels of these cofacial bis(porphinato) complexes can be lowered by 780 and 945 mV, respectively, relative to the archetypal members of this class of compounds; importantly, these orbital energy levels can be modulated over well-defined increments throughout these wide potentiometric domains. Analyses of these cofacial bis[(porphinato)metal] potentiometric data, in terms of the absolute and relative frontier orbital energies of their constituent [porphinato]zinc(II) building blocks, as well as the nature of macrocycle-to-macrocycle connectivity, provide predictive electronic structural models that rationalize the redox behavior of these species.     

A methodology for radiolabeling of the endocannabinoid 2-arachidonoylglycerol (2-AG)

The metabolic intermediate and endocannabinoid signaling lipid 2-arachidonoylglycerol (2-AG) has not been readily labeled, primarily because of its instability toward rearrangement. We now detail a synthetic method that easily gives tritiated 2-AG from [5,6,8,9,11,12,14,15-(3)H(N)]arachidonic acid in two steps. We utilized a short chain 1,3-diacylglycerol and proceeded through the "structured lipid" [5',6',8',9',11',12',14',15'-(3)H(N)]2-arachidonoyl-1,3-dibutyrylglycerol, a triacylglycerol that was conveniently deprotected in ethanol with acrylic beads containing Candida antarctica lipase B to give [5',6',8',9',11',12',14',15'-(3)H(N)]2-arachidonoylglycerol ([(3)H]2-AG). The flash chromatographic separation necessary to isolate the labeled 2-acylglycerol [(3)H]2-AG resulted in only 4% of the rearrangement byproducts that have been a particular problem with previous methodologies. This reliable "kit" method to prepare the radiolabeled endocannabinoid as needed gave tritiated 2-arachidonoylglycerol [(3)H]2-AG with a specific activity of 200 Ci/mmol for enzyme assays, metabolic studies, and tissue imaging. It has been run on unlabeled materials on over 10 mg scales and should be generally applicable to other 2-acylglycerols.     

Distance dependence of electron transfer in rigid,cofacially compressed,pi-stacked porphyrin-bridge-quinone systems

The electron-transfer (ET) dynamics of a series of unusually rigid pi-stacked porphyrin-quinone (P-Q) systems, in which sub-van der Waals interplanar distances separate juxtaposed porphyryl, aromatic bridge, and quinonyl components of these assemblies, are reported. The photoinduced charge separation (CS) and thermal charge recombination (CR) ET reactions of [5-[8'-(2',5'-benzoquinonyl)-1'-naphthyl]-10,20-diphenylporphinato]zinc(II) (1a-Zn), [5-[8'-(4'-[8'"-(2'"',5'"'-benzoquinonyl)-1'"-naphthyl]-1'-phenyl)-1'-naphthyl]-10,20-diphenylporphinato]zinc(II) (2a-Zn), and [5-(8'-[4'-(8'"-[4'"'-(8'"-[2'"',5'"'-benzoquinonyl]-1'"-naphthyl)-1'"'-phenyl]-1'"-naphthyl)-1'-phenyl]-1'-naphthyl)-10,20-diphenylporphinato]zinc(II) (3a-Zn) in CH(2)Cl(2) were investigated by pump-probe transient absorption spectroscopy. Analyses of these data show that the phenomenological ET distance dependence (beta) for both the CS and CR reactions in these systems is soft (beta(CS) = 0.43 A(-1); beta(CR) = 0.35 +/- 0.16 A(-1)). This work demonstrates that simple aromatic building blocks such as benzene, which are characterized by highly stabilized filled molecular orbitals and large HOMO-LUMO gaps, can provide substantial D-A electronic coupling when organized within a pi-stacked structural motif that features a modest degree of arene-arene interplanar compression.     

Transition state structure of E. coli tRNA-specific adenosine deaminase

Bacterial tRNA-specific adenosine deaminase (TadA) catalyzes the essential deamination of adenosine to inosine at the wobble position of tRNAs and is necessary to permit a single tRNA species to recognize multiple codons. The transition state structure of Escherichia coli TadA was characterized by kinetic isotope effects (KIEs) and quantum chemical calculations. A stem loop of E. coli tRNA(Arg2) was used as a minimized TadA substrate, and its adenylate editing site was isotopically labeled as [1'-(3)H], [5'-(3)H2], [1'-(14)C], [6-(13)C], [6-(15)N], [6-(13)C, 6-(15)N] and [1-(15)N]. The intrinsic KIEs of 1.014, 1.022, 0.994, 1.014 and 0.963 were obtained for [6-(13)C]-, [6-(15)N]-, [1-(15)N]-, [1'-(3)H]-, [5'-(3)H2]-labeled substrates, respectively. The suite of KIEs are consistent with a late SNAr transition state with a complete, pro-S-face hydroxyl attack and nearly complete N1 protonation. A significant N6-C6 dissociation at the transition state of TadA is indicated by the large [6-(15)N] KIE of 1.022 and corresponds to an N6-C6 distance of 2.0 A in the transition state structure. Another remarkable feature of the E. coli TadA transition state structure is the Glu70-mediated, partial proton transfer from the hydroxyl nucleophile to the N6 leaving group. KIEs correspond to H-O and H-N distances of 2.02 and 1.60 A, respectively. The large inverse [5'-(3)H] KIE of -3.7% and modest normal [1'-(3)H] KIE of 1.4% indicate that significant ribosyl 5'-reconfiguration and purine rotation occur on the path to the transition state. The late SNAr transition-state established here for E. coli TadA is similar to the late transition state reported for cytidine deaminase. It differs from the early SNAr transition states described recently for the adenosine deaminases from human, bovine, and Plasmodium falciparum sources. The ecTadA transition state structure reveals the detailed architecture for enzymatic catalysis. This approach should be readily transferable for transition state characterization of other RNA editing enzymes.     

Substitution, cage functionalization, and oxidation of the charge-compensated triruthenium monocarbollide cluster complex [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)6}-closo-2,1-RuCB10H8

The compound [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)6}-closo-2,1-RuCB10H8] 1a reacts with PMe3 or PCy3(Cy = cyclo-C6H11) to give the structurally different species [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)5(PMe3)}-closo-2,1-RuCB10H8] 4 and [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(CO)5(PCy3)}-closo-2,1-RuCB10H8]5, respectively. A symmetrically disubstituted product [1-SMe2-2,2-(CO)2-7,11-(mu-H)2-2,7,11-{Ru2(CO)4(PMe3)2}-closo-2,1-RuCB10H8] 6 is obtained using an excess of PMe3. In contrast, the chelating diphosphines 1,1'-(PPh2)2-Fe(eta-C5H4)2 and 1,2-(PPh2)2-closo-1,2-C2B10H10 react with 1a to yield oxidative-insertion species [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(micro-[1',1'-(PPh2)2-Fe(eta-C5H4)2])(CO)4}-closo-2,1-RuCB10H8] 7 and [1-SMe2-2,2-(CO)2-11-(mu-H)-2,7,11-{Ru2(mu-H)(CO)4(1',2'-(PPh2)2-closo-1',2'-C2B10H10)}-closo-2,1-RuCB10H8] 8, respectively. In toluene at reflux temperatures, 1a with Bu(t)SSBu(t) gives [1-SMe2-2,2-(CO)2-7-(mu-SBu(t))-11-(mu-H)-2,7,11-{Ru2(mu-H)(mu-SBu(t))(CO)4}-closo-2,1-RuCB10H8] 9, and with Bu(t)C [triple bond] CH gives [1-SMe2-2,2-(CO)2-7-{mu:eta2-(E)-CH=C(H)Bu(t)}-11-{mu:eta2-(E)-CH=C(H)Bu(t)}-2,7,11-{Ru2(CO)5}-closo-2,1-RuCB10H8] 10. In the latter, two alkyne groups have inserted into cage B-H groups, with one of the resulting B-vinyl moieties involved in a C-H...Ru agostic bond. Oxidation of 1a with I2 or HgCl2 affords the mononuclear ruthenium complex [1-SMe2-2,2,2-(CO)3-closo-2,1-RuCB10H10] 11.     

Spin transition in a chainlike supramolecular iron(II) complex

A one-dimensional supramolecular head-to-tail N+ -H...N-type hydrogen-bonded chain of the complex [FeII(L)2H](ClO4)3.MeOH [L = 4'-(4'-pyridyl)-1,2':6'1'-bis(pyrazolyl)pyridine] exhibits a reversible, thermally driven spin transition at 286 K with a hysteresis loop of ca. 2 K.     

Condensed Isoquinolines. 15. Synthesis of 5,10-Dihydro[1,2,4]triazolo[1,5-b]isoquinolines and Related Spiranes

Condensation of o-bromomethylphenylacetonitrile with arylcarbohydrazides gave, depending on the reaction conditions, 2-arylcarboxamido-1,4-dihydroisoquinoline-3(2H)-imine hydrobromides or 2-aryl-5,10-dihydro[1,2,4]triazolo[1,5-b]isoquinolines. Analogous condensation of 4-(2-bromomethylphenyl)tetrahydro-2H-pyran-4-carbonitrile and 1-(2-bromomethylphenyl)-1-cyclopentanecarbonitrile with arylcarbohydrazides gave respectively 2-aryl-2,3,5,6-tetrahydrospiro[4H-pyran-4,10'(5'H)-[1,2,4]triazolo[1,5-b]isoquinolines and 2-arylspiro[1,2,4]triazolo[1,5,b]isoquinoline-10(5'H)-1'-cyclopentanes, derivatives of new spirane heterocycles. The reaction with condensing agents of 3-imino-2,2',3,3'5',6'-hexahydrospiro[isoquinoline-4(1H),4'-4H-pyran]-2-amine and 3-imino-2,3-dihydrospiro[isoquinoline-4(1H),1'-cyclopentane]-2-amine hydrobromides, synthesized from the corresponding bromo nitriles and hydrazine, may serve as an alternative route for the synthesis of these compounds. The structure of obtained triazoloisoquinolines was established from IR, ¹H and ¹³C NMR spectra. An X-ray crystallographic study of 2-phenylspiro[1,2,4]triazolo[1,5-b]isoquinoline-10(5H),1'-cyclopentane was carried out.     

2-芳胺基-5-[5′-氨基-1′-(4″-氯苯基)-1′,2′,3′-三唑-4′-基]-1,3,4-噻二唑的合成~≠

1-[5’-氨基-1’-(4”-氯苯基)-1,2,3-三唑-4’-甲酰基]-4-芳基-3-氨基硫脲在浓硫酸催化下环化得到2-芳胺基-5-[5’-氨基-1’-(4”-氯苯基)-1’,2’,3’,-三唑-4’-基]-1,3,4-噻二唑2a～i,依次法合成了九个标题化合物,收率为30～74％。化合物2i的结构用X-光衍射单晶分析确证。     

A new family of Ru complexes for water oxidation

Reaction of the bridging ligand 3,6-bis-[6'-(1' ',8' '-naphthyrid-2' '-yl)-pyrid-2'-yl]pyridazine (1) with [Ru(DMSO)4Cl2] in aqueous ethanol followed by excess 4-substituted pyridine (4-R-py) in the presence of triethylamine provides a series of three well-organized dinuclear complexes characterized by 1H NMR, MS, and X-ray. Mononuclear analogues are prepared from 4-tert-butyl-2,6-di(1',8'-naphthyrid-2'-yl)pyridine (5) and characterized in a similar fashion. All six complexes show electronic absorption and redox properties consistent with the electron donor/acceptor ability of the axial 4-R-py ligand. When an acetonitrile solution of the catalyst is added to an aqueous Ce(IV)-CF3SO3H solution (pH = 1.0) at 24 degrees C, oxygen evolution is observed for both mono and dinuclear systems. Turnover numbers range from 50 to 3200 with the best results being found when the axial ligand is 4-methylpyridine (mononuclear TN = 580 and dinuclear TN = 3200).     

Novel photochromic spiroheterocyclic molecules via oxidation of 1,8-diaminonaphthalene

[reaction: see text] Novel spiroheterocyclic molecules, namely, 2,3-dihydro-2-spiro-7'-[8'-imino-7',8'-dihydronaphthalen-1'-amine]perimidine, PNI, and 2,3-dihydro-2-spiro-4'-[8'-aminonaphthalen-1'(4H)-one]perimidine, PNO-p, were obtained by oxidation of 1,8-diaminonaphthalene using manganese dioxide. These molecules exhibit thermally reversible photochromism with good photofatigue resistance, and their photogenerated forms possess broad absorption in the visible region.     

Diorganodiselenides and zinc(II) organoselenolates containing (imino)aryl groups of type 2-(RN=CH)C6H4

Several new diorganodiselenides containing (imino)aryl groups, [2-(RN[double bond, length as m-dash]CH)C(6)H(4)](2)Se(2) [R = Me(2)NCH(2)CH(2) (4), O(CH(2)CH(2))(2)NCH(2)CH(2) (5), PhCH(2) (6), 2',6'-(i)Pr(2)C(6)H(3) (7)] were obtained by reacting [2-{(O)CH}C(6)H(4)](2)Se(2) (3) with RNH(2). Treatment of the diselenides 6 and 7 with stoichiometric amounts of K-selectride or Na resulted in isolation of the selenolates K[SeC(6)H(4)(CH[double bond, length as m-dash]NCH(2)Ph)-2] (9) and Na[SeC(6)H(4)(CH[double bond, length as m-dash]NC(6)H(3)(i)Pr(2)-2',6')-2] (10), respectively. The reaction of potassium selenolates with anhydrous ZnCl(2) (2:1 molar ratio) gave Zn[SeC(6)H(4)(CH=NCH(2)Ph)-2](2) (11) and Zn[SeC(6)H(4)(CH[double bond, length as m-dash]NC(6)H(3)(i)Pr(2)-2',6')-2](2) (12). When the dark green solution obtained from diselenide 7 and an excess of Na (after removal of the unreacted metal) was reacted with anhydrous ZnCl(2) a carbon-carbon coupling reaction occurred and the 9,10-(2',6'-(i)Pr(2)C(6)H(3)NH)(2)C(14)H(10) (8) species was obtained. The compounds were investigated in solution by multinuclear NMR ((1)H, (13)C, (77)Se, including 2D and variable temperature experiments) and by mass spectrometry. The molecular structures of 6, 8, 11 and 12 were established by single-crystal X-ray diffraction. All compounds are monomeric in the solid state. In the diselenide 6 the (imino)aryl group acts as a (C,N)-ligand resulting in a distorted T-shaped coordination geometry of type (C,N)SeX (X = Se). For the zinc complexes 11 and 12 the (Se,N) chelate pattern of the selenolato ligands results in tetrahedral Zn(Se,N)(2) cores.