Structure,tautomerism, and transformations of β-(3-nitro-2-pyridyl)- and β-(3-nitro-4-pyridyl)pyruvic acid esters

It was shown by means of IR, UV, and PMR spectra that -(3-nitro-2-pyridyl)pyruvic acid esters are practically completely enolized in the crystal state and in solution; ethyl -(3-nitro-4-pyridyl)pyruvate has an enol structure in the crystalline state and in pyridine solution but exists as a mixture of keto and enol forms in low-polarity solvents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 389–393, March, 1974.     

Course of bromination of thiazole and 2-methylthiazole

Bromination of thiazole by bromine in the presence of aluminum chloride in neutral solvent or without solvent takes place at the 2-position. Such an orientation contradicts the traditional addition-cleavage mechanism, and agrees with the ylid mechanism of electrophilic substitution. 2-Methylthiazole brominates at the 5-position, and the reaction is impeded in the presence of aluminum chloride; this is due to heterocycle deactivation by complexation with the Lewis acid at the nitrogen atom.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 837–840, June, 1986.     

Hydrocarbomethoxylation of 1-hexene with formic acid and methanol under conditions of phosphoric acid catalysis

Conclusions When the hydrocarbomethoxylation of 1-hexene with formic acid is run at atmospheric pressure and temperatures close to room temperature, in the presence of conc. H₃PO₄, an increase in the relative amount of the latter, as well as an increase in the reaction temperature in the investigated range, both favor an increase in the yields of the methyl esters of the C₇ acids, in particular, those containing two methyl groups on the quaternary carbon atom in the -position. An increase in the relative amount of formic acid also favors an increase in the amounts of these esters in the obtained mixtures of esters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1116–1118, May, 1971.     

Hydrolysis of furan and 5-nitrofuran penicillins by penicillinase Bacillus licheniformis

The enzymatic hydrolysis of various furan and 5-nitrofuran penicillins by penicillinaseBacillus licheniformis 749/c was investigated. The effect of various side-chain structural groupings on the rate of inactivation of these compounds was studied. The introduction of bulky substituents in the ortho or positions to the amide group and lengthening the side chain or increasing its degree of unsaturation sharply decrease the catalytic action of penicillinase and, consequently, the rate of cleavage of the-lactam ring of the antibiotic. The majority of the furan and 5-nitrofuran penicillins surpass benzylpenicillin in resistance to the enzyme but are inferior to methicillin and oxacillin.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 295–298, March, 1971