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  • 1
    Electronic Resource
    Electronic Resource
    Boron heterocycles derived from 2-guanidinobenzimidazoleDedicated to Prof. Heinrich Nöth on the occasion of his seventieth birthday. (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 9 (1998), S. 399-409 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses and structure determinations of a series of boron heterocycles derived from 2-guanidinobenzimidazole 1 are reported. Structures of new compounds, 2-guanidino-1-methyl-benzimidazole 2, diphenyl-(2-guanidinobenzimidazole-N,N′)-borate 3, diphenyl-(2-guanidino-1-methyl-benzimidazole-N,N′)borate 4, hydroxy-phenyl-(2-guanidino-benzimidazole-N,N′)borate 5, hydroxy-phenyl-(2-guanidino-1-methyl-benzimidazole-N,N′)borate 6,methoxy-phenyl-(2-guanidinobenzimidazole-N,N′)borate 7, isopropoxy-phenyl-(2-guanidinobenzimidazole-N,N′)borate 8, acetoxy-phenyl-(2-guanidinobenzimidazole-N,N′)borate 9, methoxy-phenyl-(2-guanidino-1-methyl-benzimidazole-N,N′)borate 10, dihy-droxy-(2-guanidino-1-methyl-benzimidazole-N,N′)borate 16, difluoro-(2-guanidinobenzimidazole-N,N′)borate, 17, dihydroxy-(2-guanidino-1-benzimidazole-N,N′)borate potassium salt 19, diphenyl-(2-guanidinium-10H-benzimidazole-N,N′)borate hydro-chloride 20, methoxy-phenyl-(2-guanidinobenzimidazole-N,N′)borate hydrochloride 21, and N10-borane-(diphenyl-2-guanidinobenzimidazole-N,N′)borate 22, were determined based on 1H, 13C, 15N, and 11B spectroscopy. The X-ray diffraction structures of 3-7, 19, and 20 were obtained. The formation of N3-borane adducts 11 and 12 derived from compounds 1 and 2, respectively, and the dihydride-(2-guanidinobenzimidazole-N,N′)borate 13 and dihydride-(2-guanidino-1-methyl-benzimidazole-N,N′)borate 14 were observed by 11B NMR. The results show that 2-guanidinobenzimidazole gives stable borate heterocycles with a delocalized π electronic system. A dynamic exchange of N-H protons was observed with preferred protonation at N-12. The new heterocycles are protonated at N-10 by acidic substances to give pyridinium-type heterocycles or can lose a proton to give iminium salts. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:399-409, 1998
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Organometallic tin complexes derived from 2-guanidinobenzimidazole (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 9 (1998), S. 637-641 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coordination compounds derived from 2-guanidinobenzimidazole 1 and R2SnCl2 (2 R = Me, 3 R = Bu, 4 R = Ph), and SnCl4 7 were prepared and their structures investigated by 1H, 13C, 119Sn, 15N NMR, mass spectrometry (FAB or EI), infrared, and elemental analysis. The NMR data suggest pentacoordinated (5 and 6) or hexacoordinated tin atoms 2-4 and 7. In all cases, 2-guanidinobenzimidazole acts as a bidentate ligand. In the solid state, 2-4 and 7 are associated by bridging chlorine atoms in polymeric chains. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9: 637-641, 1998
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Benzazole-N(SINGLE BOND)BH3 adducts. Reductive transposition of 2-benzimidazole, 2-benzothiazole, and 2-benzoxazole N(SINGLE BOND)BH3 adducts to 1,3,2-benzimidazaborole, 1,3,2-benzoxaborole, and 1,3,2-benzothiazaborole (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 7 (1996), S. 323-335 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3,2-Benzimidazaborole, 1,3,2-benzoxaborole, and 1,3,2-benzothiazaborole were synthesized from the corresponding 2-benzazole N(SINGLE BOND)BH3 and 2-benzazole S(SINGLE BOND)BH3 adducts through a reductive transposition from the isolobal fragment X(SINGLE BOND)C(sp2) (DOUBLE BOND) N(sp2) (SINGLE BOND) B(sp3) (X (DOUBLE BOND) N, O, S) to the fragment X(SINGLE BOND)B(sp2) (DOUBLE BOND) N(sp2) (SINGLE BOND) C(sp3). N(SINGLE BOND)BH3 substitution shifts to lower frequencies 4-H, C-3a, and C-7a resonances. The X-ray diffraction analysis of 2-(o-methoxyphenyl)benzothiazole N(SINGLE BOND)BH3 adduct is reported. Two new tetracyclic boron-bridged compounds were observed as by-products (6,9-(ethyl)-diaza-2-oxa-1-bora[3,4,7,8]-dibenzobycyclo[4.3.0]-nona-3,7-diene, 6d, and 8-aza-9-oxa-2-thia-1-bora-[3,4,7,8]dibenzobycyclo[3.4.0]nona-3,7-diene, 15d, when 2-(o-methoxyphenyl)-1-ethylbenzimidazole-BH3 6b and 2-(o-methoxyphenyl)-benzothiazole-BH3 15b adducts were heated. © 1996 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Versatile behavior of 2-guanidinobenzimidazole nitrogen atoms toward protonation, coordination and methylation (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 8 (1997), S. 397-410 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure, dynamic behavior, protonation, methylation, and coordination sites of 2-guanidinobenzimidazole 1a were investigated. Structures of compounds [2-guanidinium-1,3,10-trihydrobenzimidazole]sulfate 1b, [2-guanidinium-1,3-dihydro-benzimidazole]sulfate 1c-1d, [2-guanidinium-1,3-dihydro-benzimidazole]tetrafluoroborate 1e, [2-guanidinium-1,3-dihydro-benzimidazole]chloride 1f, [2-guanidinium-1,3-dihydro-benzimidazole] perchlorate 1g, 2-guanidino-1-methyl-benzimidazole 2a, [2-guanidinium-1,3-dimethyl-benzimidazole]iodide 2b, [2-guanidinium-1-methyl-3-hydro-benzimidazole]chloride 2c, [2-guanidinium-1,10-dihydro-benzimidazole]acetate 3, 2-guanidino-1-hydro-3-borane-benzimidazole 4a, 2-guanidino-1-methyl-3-borane-benzimidazole 4b, (2-guanidino-benzimidazole)dimethyltin 5, [bis(2-guanidino-10-hydro-benzimidazole)nickel(II)] 6, and [bis(2-guanidino-1,10-dihydro-benzimidazole)zinc(II)]nitrate 7 were determined based on 1H, 13C, and 15N NMR spectroscopy. The X-ray diffraction structures of 2a, 2b, 3, 6, and 7 were obtained. The results show that 1a has an open structure without an intramolecular hydrogen bond in DMSO or DMF. The imidazolic N-3 is the preferred basic site in solution for protonation, methylation, and coordination and not N-10 as was suggested from semiempirical calculations. Under strong acidic conditions, diprotonation occurs at N-3 and N-10. In the solid state, 3 and 6 were protonated preferently at N10 rather than at N-1. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 397-410, 1997
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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