Kinetics and mechanism of formation of isomeric 1-methyl- and 2-methyl-5-vinyltetrazoles

The alkylation of 5-(β-dimethylaminoethyl)tetrazole (1) with dimethyl sulfate afforded 5-(β-dimethylaminoethyl)-1-methyltetrazole (2) and 5-(β-dimethylaminoethyl)-2-methyltetrazole (3). The exhaustive alkylation of compounds 2 and 3 at the terminal dimethylamino group gave 1-methyl-(4) and 2-methyl-5-(β-trimethylammonioethyl)tetrazole (5) methyl sulfates. The proton elimination from the α-methylene (with respect to the tetrazole cycle) groups of the quaternary ammonium cations of salts 4 and 5 by the action of a base leads to the corresponding zwitterions 4 ^± and 5 ^±, which in the rate-determining step undergo the cleavage of the nitrogen—carbon bond with the formation of 1-methyl-5-vinyl- (6) and 2-methyl-5-vinyltetrazole (7). The true constant of the transformation of zwitterion 4 ^± into tetrazole 6 is 21 times higher than that for the transformation of zwitterion 5 ^± into tetrazole 7.     

2-p-Chlorphenyl-3-methyl-2,3-butandiol (Phenaglycodol)

Ohne Zusammenfassung     

Nitrate and perchlorate salts of a silver(I) complex from 5-methyl-2-(2,3-diaza-4-(5-methyl-2-thienyl)buta-1,3-dienyl)thiophene

Bis(5-methyl-2-(2,3-diaza-4-(5-methyl-2-thienyl)buta-1,3-dienyl)thiophene) silver(I) complex was synthesized in high yield by refluxing 5-methyl-2-(2,3-diaza-4-(5-methyl-2-thienyl)buta-1,3-dienyl)thiophene (L) with silver nitrate or silver perchlorate in anhydrous acetonitrile. The product thus formed was well characterized by NMR, IR, UV–Vis and mass spectroscopies as well as elemental analysis and electrochemical analysis. Molecular structures of compounds L, [L₂Ag]NO₃ and [L₂Ag]ClO₄ were determined by single crystal X-ray diffraction analysis. It was found that the C=N double bond of the ligand rotated during the course of ligand coordination in the case of the perchlorate salt but not in the case of the nitrate salt.     

Cyclization reactions 31. Synthesis of 2-methyl-2-halomethylbenzimidazo [2,1-b]thiazolidinium salts and their conversions to N-(2-methyl-2,3-epithio-propyl)benzothiazol-2-ones

In a novel synthesis, from 2-methyl-2-halomethylbenzimidazo[2,1-b]thiazolidinium salts, by means of their recyclization under the influence of alkali, N-(2-methyl-2, 3-epithiopropyl)benzimidazol-2-ones have been obtained. Syntheses of the indicated salts from N-methallylbenzimidazole-2-thiones are described.Institute of Physical Organic Chemistry and Coal-Tar Chemistry, Academy of Sciences of the Ukraine, Donetsk 3400114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 706–710, May, 1994. Original article submitted May 4, 1994.     

Mass spectrometric fragmentation patterns of isomeric 5-methyl-3-alkyl-2-alkenylpyrazines

The detailed mass spectral fragmentation pathways of a series of both naturally occurring and synthetic 5-methyl-3-alkyl-2-aIkenylpyrazines have been elucidated with the aid of deuterium labels placed specifically in the alkenyl side-chain. The influence on the fragmentation pattern of the stereochemistry of the alkenyl group as well as the relative placement of the groups on the pyrazine nucleus have also been evaluated. This provides information of some diagnostic value in the assignment of structures by mass spectrometry to new compounds within this class.     

Synthesis of 5(and 6)-nitro-4-methyl-2,3-dihydro-1h-1,5-benzo-2-diazepinones

The reaction of 4-nitro-o-phenylenediamine (I) with acetoacetic ester at room temperature under acid catalysis gives ethyl 3-(2-amino-5-nitrophenylamino)crotonate (II), which is readily cyclized to 7-nitro-4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone (III) on heating with alkaline agents. The reaction of I with acetoacetic ester in refluxing xylene gives isomeric 8-nitro-4-methyl-2,5-dihydro-1H-1,5-benzo-2-diazepinone (IVa) or 8-nitro-4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone (IVb), which are readily interconverted. The synthesis of IV is complicated by the side formation of 5-nitro-2-methylbenzimidazole (V) and thermal rearrangement of IVa and IVb to 5-nitro-1-isopropenylbenzimidazolone (VI). 6-Nitro-1-isopropenylbenzimidazolone (VII) is similarly obtained on heating III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 696–699, May, 1972.