Comparison of 13C and 1H N-alkyl shifts of isomeric alkyl tetrazoles: some ambident benzylations

Butler, R. N.; McEvoy, T. M.; Scott, F. L.; Tobin, J. C.

doi:10.1139/v77-217

Cited by 25 publications

(3 citation statements)

References 6 publications

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“…N-1 and N-2 isomeric tetrazoles can be readily distinguishable by their 1 H and 13 C NMR spectra. According to Butler 21 and others, 18,22 C-5 resonates at ca. d 150 ppm for N-1 tetrazole and at ca.…”

Section: Synthesismentioning

confidence: 98%

Synthesis and characterization of some novel tetrazole liquid crystals

et al. 2013

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The synthesis and characterization of new 4-[(2-alkyl)-2H-tetrazol-5-yl]phenyl 4-alkyloxybenzoates (5a-i) and 5-{4-[(4-substituted)benzyloxy]phenyl}-2-alkyl-2H-tetrazoles (7a-e) are reported. The reported tetrazoles contain two alkyl chains (six to ten carbon atoms) except for 5h and 7e which have a chiral citronellyl group linked at the N-2 nitrogen atom of the tetrazole ring and 5i having a bromine atom at the para position of benzoate. The regiochemistry in the alkylation step was established unequivocally by single-crystal X-ray analysis for 5a and 5f. The regioselectivity in the alkylation step was also confirmed by analysis of 13 C NMR chemical shifts of the C 5 carbon atom in the tetrazole ring and the methylene carbon atom vicinal to the nitrogen atom. The mesogenic behavior of the liquid crystals was characterized by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The tetrazolyl benzoates 5a-h show a nematic mesophase. The lengthening of alkyl chains favors the appearance of the smectic mesophase. For instance, 5g displayed nematic and smectic C mesophases, while 5h which has the chiral citronellyl group displayed nematic and smectic A mesophases. Tetrazoles 7a-e did not show mesomorphic behavior mainly due to replacement of the carbonyl by a methylene group.

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Section: Synthesismentioning

confidence: 98%

Synthesis and characterization of some novel tetrazole liquid crystals

et al. 2013

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“…0.15-0.35 ppm in the 1 H spectra and by ca. 2-6 ppm in the 13 C spectra to their corresponding N-2 isomers 9 . The regioselectivity in the alkylation was confirmed by the analysis of the 13 C NMR chemical shifts of the carbon atom C5 in the tetrazole ring.…”

Section: Phenyltetrazole Ligandsmentioning

confidence: 98%

Synthesis, characterization and thermal properties of palladium(II) complexes containing phenyltetrazole. Crystal structure of trans-[C40H64N8 O2PdCl2]

Gallardo¹,

Begnini²,

Neves³

et al. 2000

J. Braz. Chem. Soc.

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Neste trabalho, descreve-se a síntese de novos ligantes e dos seus complexos de Pd(II) com os ligantes 5-(n-alcoxifenil)-2-n-alquiltetrazol (L 1 ) e α,ω-bis-[5-(4-pentoxifenil)-2-alcanotetrazois] (L 2 ). A determinação estrutural através de difração de raios-X do complexo de paládio contendo L 1 revela uma estrutura mononuclear na qual a geometria do cromóforo Pd(L 1 ) 2 Cl 2 é plana e possui um centro de inversão sobre o átomo de paládio. As moléculas de feniltetrazol estão ligadas ao íon metálico de forma monodentada e trans entre si, através de uma ligação σ, Pd-N1. Para o complexo de paládio contendo L 2 , propõe-se uma estrutura dinuclear, ([Pd 2 (L 2 ) 2 Cl 4 ]), com base em dados de espectroscopia de RMN e IV.The new 5-(n-alkoxyphenyl)-2-n-alkyltetrazole (L 1 ) and α,ω-bis-[5-(4-pentoxyphenyl)-2-alkanetetrazoles] (L 2 ) ligands and their Pd(II) complexes have been synthesized. The X-ray diffraction study of the palladium complex with L 1 reveals a mononuclear structure in which the geometry of the Pd(L 1 ) 2 Cl 2 chromophore is planar as required by the inversion center at the palladium atom, where each molecule of phenyltetrazole binds to the metal ion in a monodentate fashion via a Pd-N1 σ-bond. For the palladium complex with L 2 , a dinuclear structure ([Pd 2 (L 2 ) 2 Cl 4 ]) has been proposed on the basis of NMR and IR spectroscopy.

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“…The observed difference of the chemical shifts for the two isomeric compounds calculated as Δδ = δ2,5-isomer − δ1,5-isomer lies in the range of 10.6-12.0 ppm [26,28,29]. Moreover, it has been also shown that the 13 C-NMR chemical shifts of tetrazole N-Cα (TN-Cα) carbon atom of 2,5-disubstituted tetrazoles are higher compared to the corresponding resonances in the 1,5-disubstituted isomers [10,26,31,32]. Therefore, comparison of 13 C-NMR data of 2, 3, 6, 9 and 10 with those presented for 2,5-and 1,5-disubstituted tetrazoles allows unambiguously identifying and differentiating isomeric N-1-and N-2-substituted tetrazoles.…”

Section: Determination Of the Structure Of The Bromide 2 And The Intementioning

confidence: 99%

Synthesis and Physicochemical Characterization of the Process-Related Impurities of Olmesartan Medoxomil. Do 5-(Biphenyl-2-yl)-1-triphenylmethyltetrazole Intermediates in Sartan Syntheses Exist?

et al. 2015

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During the process development for multigram-scale synthesis of olmesartan medoxomil (OM), two principal regioisomeric process-related impurities were observed along with the final active pharmaceutical ingredient (API). The impurities were identified as N-1-and N-2-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl derivatives of OM. Both compounds, of which N-2 isomer of olmesartan dimedoxomil is a novel impurity of OM, were synthesized and fully characterized by differential scanning calorimetry (DSC), infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectrometry/electrospray ionization (HRMS/ESI). Their 1 H, 13 C and 15 N nuclear magnetic resonance signals were fully assigned. The molecular structures of N-triphenylmethylolmesartan ethyl (N-tritylolmesartan ethyl) and N-tritylolmesartan medoxomil, the key intermediates in OM synthesis, were solved and refined using single-crystal X-ray diffraction (SCXRD). The SCXRD study revealed that N-tritylated intermediates of OM exist exclusively as one of the two possible regioisomers. In molecular structures of these regioisomers, the trityl substituent is attached to the N-2 nitrogen atom of the tetrazole ring, and not to the N-1 nitrogen, as has been widely reported up to the present. This finding indicates that the reported structural formula of N-tritylolmesartan ethyl and N-tritylolmesartan medoxomil, as well as their systematic chemical names, must be revised. The careful analysis of literature spectroscopic data for other sartan intermediates and their analogs with 5-(biphenyl-2-yl)tetrazole moiety showed that they also exist exclusively as N-2-trityl regioisomers.

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Comparison of ¹³C and ¹H N-alkyl shifts of isomeric alkyl tetrazoles: some ambident benzylations

Cited by 25 publications

References 6 publications

Synthesis and characterization of some novel tetrazole liquid crystals

Synthesis and characterization of some novel tetrazole liquid crystals

Synthesis, characterization and thermal properties of palladium(II) complexes containing phenyltetrazole. Crystal structure of trans-[C40H64N8 O2PdCl2]

Synthesis and Physicochemical Characterization of the Process-Related Impurities of Olmesartan Medoxomil. Do 5-(Biphenyl-2-yl)-1-triphenylmethyltetrazole Intermediates in Sartan Syntheses Exist?

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