- An Environmentally Friendly Method for N-Methylation of 5-Substituted 1H-Tetrazoles with a Green Methylating Reagent: Dimethyl Carbonate
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An environmentally friendly method was established for the N-methylation of the 5-substituted 1H-tetrazoles with a green reagent: DMC. DABCO was the optimal catalyst, and hazardous chemicals were avoided in this protocol. A plausible catalytic mechanism is proposed, which consists of a DABCO-activated process and a thermally induced rearrangement of tetrazole carbamates.
- Xie, Aming,Zhang, Qiang,Liu, Yangyang,Feng, Liandong,Hu, Xinyu,Dong, Wei
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p. 1483 - 1487
(2015/10/06)
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- A facile and convenient synthesis of substituted tetrazole derivatives from ketones or α,β-unsaturated ketones.
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Triazidochlorosilane (SiCl4-NaN3 in situ) is a new and efficient reagent for the direct conversion of ketones or α,β-unsaturated ketones to the corresponding tetrazole derivatives in nearly quantitative yield.
- El-Ahl, Abdel-Aziz S.,Elmorsy, Saad S.,Soliman, Hanan,Amer, Fathy A.
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p. 7337 - 7340
(2007/10/02)
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- Controlled Synthesis of 5-Substituted 1-Methyl-1H-Tetrazoles and 3,5-Disubstituted 1,4-dimethyltriazolium Salts from N-Methylnitrilium Trifluoromethanesulfonate Salts.
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C-Alkyl and -benzyl N-methylnitrilium trifluoromethanesulfonate salts, 1C=NMe>+ OTf- (R1=Me, Prn, Pri, But, PhCH2; OTf=O3SCF3), react rapidly under mild conditions with either sodium azide or tetramethylguanidinium azide in nitromethane to give the corresponding 5-substituted 1-methyl-1H-tetrazoles as the sole product in high yields.These reactions are independent of the mode of addition.C-aryl-N-methylnitrilium trifluoromethanesulfonate salts (R1=C6H6, 2-MeC6H4, 4-MeC6H4, 2,4-Me2C6H3) give mixtures of the corresponding tetrazoles and the triazolium salts with sodium azide.With tetramethylguanidinium azide the products depend upon the mode of addition.Addition of the nitrilium salt to the azide gives only the tetrazole, while inverse addition gives the triazolium salt in high yield.
- Amer, Muhanned I. K.,Booth, Brian L.
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p. 113 - 124
(2007/10/02)
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- TETRAZOLES. XXVIII PREPARATION AND PROPERTIES OF 2,3-DIPHENYL-5-ALKYLTETRAZOLIUM SALTS
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The oxidation of 1,5-diphenyl-3-alkylformazanes by potassium permanganate in methylene chloride (chloroform)-water two-phase systems is a convenient method for the preparation of 2,3-diphenyl-5-alkyltetrazolium salts.The 2,3-diphenyl-5-alkyltetrazolium salts can be used as catalysts for interphase transfer in reactions proceeding in organic solvent-water two-phase systems, with a neutral or acid aqueous phase.The catalytic activity of 2,3-diphenyl-5-alkyltetrazolium salts increases with increase in the length of the alkyl substituent in the 5-position of the tetrazole ring.
- Nikonova, I. V.,Koldobskii, G. I.,Zhivich, A. B.,Ostrovskii, V. A.
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p. 1951 - 1957
(2007/10/02)
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- Photochemical Formation of Heteromethylenecyclopropanes, 16. - 1,4,5-Substituted Tetrazolium Salts Through Methylation of 1,5-Substituted Tetrazoles and Cycloaddition of Alkyl Azides to Nitrilium Ions
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Efficient syntheses of isomerically pure 1,4,5-substituted tetrazolium salts are reported.Methylation of 1,5-substituted tetrazoles 5 affords mixtures of 1,4,5- (1) and 1,3,5-substituted tetrazolium salts 6.The ratio 1:6 depends only little on the reaction conditions as well as on the methylating agents.The isomerically pure tetrazolium salts 1a-e, g, j, k and 6j, k are isolated by fractionating crystallizations. tert-Butylation of 5a, c using tert-butyl alcohol/tetrafluoroboric acid produces only the 3-tert-butyltetrazolium tetrafluoroborates 9a, c.The N-methylnitrili um tetrafluoroborates, fluorosulfonates or trifluoromethanesulfonates 7a-c and e cycloadd the alkyl azides 8a-d regioselectively to the tetrazolium salts 1a-c, e, f, h, i.Both rate and yield of the cycloaddition decrease with increasing size of the substituents.The N-tert-butylnitrilium tetrachloroferrate 7h (X=FeCl4) reacts with methyl azide (8a) yielding the hydrogen tetrachloroferrate 4a*HFeCl4 of the imidoyl chloride 4a.
- Quast, Helmut,Bieber, Lothar,Meichsner, Georg
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p. 469 - 476
(2007/10/02)
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- Reaction of Trimethylsilyl Azide with C=N-O Bond
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Trimethylsilyl azide (TMSA) was reacted with an oxime ester or a Reissert salt in the presence of trimethylsilyl trifluoromethanesulfonate to give tetrazole derivative.The details of these reactions are examined.
- Nishiyama, Kozaburo,Miyata, Izumi
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p. 2419 - 2420
(2007/10/02)
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- ADDITION REACTION OF TRIMETHYLSILYL AZIDE TOWARDS KETONES AND FACILE FORMATION OF TETRAZOLE DERIVATIVES
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In the presence of Lewis acid such as SnCl2, the reactions of trimethylsilyl azide with ketones readily gave 1:1- or 1:2-adduct, which reacted with Lewis acid to afford tetrazole.
- Nishiyama, Kozaburo,Watanabe, Akio
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p. 455 - 458
(2007/10/02)
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- TETRAZOLES. XVI. ALKYLATION OF TETRAZOLES UNDER THE CONDITIONS OF PHASE-TRANSFER CATALYSIS
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The alkylation of tetrazole and 5-substituted tetrazoles with dimethyl sulfate and methyl iodide in the two-phase methylene chloride-water system in the presence of tetrabutylammonium bromide was investigated.The alkylation of tetrazoles with methyl iodide takes place in the organic phase, while that with dimethyl sulfate takes place both in the organic and in the aqueous phases.The ratio of the isomeric tetrazoles formed during the alkylation of 5-aryltetrazoles by methyl iodide correlate with the substituent constants ?.The use of phase-transfer catalysis during the alkylation of tetrazoles does not lead to a change in the selectivity of the reaction.
- Osipova, T. F.,Ostrovskii, V. A.,Koldobskii, G. I.,Erusalimskii, G. B.
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p. 357 - 362
(2007/10/02)
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- Positional Selectivity of the Methylation of 5-Substituted Tetrazolate Anions
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The methylation of a series of 15 sodium 5-substituted tetrazolates using iodomethane in acetone/water (4:1) has been studied.The reaction yields both 1- and 2-methyl products, and the ratio of these products is discussed in terms of the nature of the 5-substituent.Electronic and steric effects dominate the reaction pathway; both increased substituent electronegativity and steric bulk lead to predominant methylation at N 2.Sodium 5-ethoxycarbonyltetrazolate (3n) goes against this trend and an intermediate is proposed where the incoming electrophile is associated with the ester carbonyl group.
- Spear, Robert J.
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p. 2453 - 2468
(2007/10/02)
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- Regiospecific Coordination of Ambidentate Tetrazoles to Cobalt Oximes
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A series of complexes of the type (n-Bu3P)Co(DH)2(5R-tetrazolate) (DH is the monoanion of dimethylglyoxime; R = CF3, CH3, C6H5, C6H5CH2, (CH3)2N, 4-FC6H4, and 3-FC6H4) have been prepared and characterized by conductance studies, elemental analyses, and 1H, 13C, 31P, and 19F NMR spectroscopy.Quantum-mechanical calculations (MINDO/3) indicate that the N1 nitrogens of the aromatic tetrazolate anion are slightly more nucleophilic than the N2, yet in each complex the ambidentate tetrazolate anion is coordinated to cobalt via the N2 nitrogen, showing that regiospecific coordination is sterically induced.This is in marked contrast to tetrazole complexes of platinum and palladium wherein both N1 and N2 bound tetrazoles are found in approximately equal abundances.These cobalt complexes react with alkyl halides such as CH3I and C6H5CH2Br to produce exclusively 1,5-disubstituted tetrazoles.None of the isomeric 2,5-disubstituted tetrazole is detected in these reactions in marked contrast to the reactions of sodium tetrazolates or gold, palladium, or platinum tetrazolate complexes with alkyl halides which produce mixtures of the 1,5- and 2,5-disubstituted tetrazoles.The crystal structure of n-Bu3PCo(DH)2(5-CF3-tetrazolate) was determined using three-dimensional X-ray diffraction techniques.The molecule crystallizes in the orthorhombic space group Pbca in a unit cell of dimensions a = 12.040(2) Angstroem, b = 21.531(3) Angstroem, c = 23.536(4) Angstroem, ρcalcd = 1.368 g/cm3, ρobsd = 1.374 g/cm3.Refinement converged to 5.4percent with 2525 independent reflections.The tetrazolato ring is coordinated to cobalt via N2 and is planar.The Co-P bond (2.263 Angstroem) is one of the shortest observed in LCo(DH)2X structures.The acute dihedral angle between the planes of the two glyoximato groups (10.4 deg) is among the largest dihedral angles observed in structures of this type.Surprisingly, the tetrazolato ring does not lie in the fold of the two glyoximato rings but is nearly normal to it.Thus, the regiospecificity of the alkylations of the coordinated tetrazolate with alkyl halides is sterically promoted.
- Takach, Nicolas E.,Holt, Elizabeth M.,Alcock, Nathaniel W.,Henry, Ronald A.,Nelson, John H.
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p. 2968 - 2979
(2007/10/02)
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