TETRAZOLES. XVI. ALKYLATION OF TETRAZOLES UNDER THE CONDITIONS OF PHASE-TRANSFER CATALYSIS
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.
p. 357 - 362
(2007/10/02)
Positional Selectivity of the Methylation of 5-Substituted Tetrazolate Anions
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.
p. 2453 - 2468
(2007/10/02)
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