G. D. Kalayanov

Structure and conformational mobility of substituted imidazodiazepinediones

Two-dimensional (NOESY) and dynamic IH NMR spectroscopy was used to determine the structure and conformational mobility of substituted 1,4,7-trimethyl-4,5,7,8-6H-imidazo[4,5-e][l,4]-diazpene-5,6-diones, which are cyclic homologs of caffeine, a natural alkaloid. 13C NMR spectroscopy was used to determine the activation energy for inversion of the seven-membered ring, which was related to the electronic effect of substituents. Computer models were obtained for the predominant conformations of the compounds studied.

Synthesis and molecular structure of 1,4-dimethyl-4,5,7,8-tetrahydro-6H-imidazo[4,5-e][1,4]-diazepine-5,8-dithione

Abstract1,4-dimethyl-4,5,7,8-tetrahydro-6H-imidazo[4,5-e][1,4]-diazepine-5,8-dithione was synthesized by boiling 1,4-dimethyl-4,5,7,8-tetrahydro-6H-imidazo[4,5-e][1,4]-diazepine-5,8-dione (a cyclic homolog of theobromine) with P2S5. Its molecular and crystal structures were determined by X-ray structure analysis, PMR spectroscopy and the calculations using the MM2 program. The crystals are monoclinic, sp. gr. P21/n with a=9.305(4), b=9.464(3), c=11.628(3) Å, γ-90.49(3)o, Z=4 for C8H10N4S2. M.p. 268–269 °C. The 7-membered heterocycle has a boat conformation in the crystal, while in solution at room temperature it undergoes interconversion. The geometrical parameters of the molecule obtained by X-ray structure analysis, by PMR spectroscopy below the coalescence temperature (290 K), and by MM2 calculations are in good agreement.

Synthesis of imidazo[4,5-e][1,4]diazepine-8-one

We have developed a method for synthesis of 1-methyl-4,5,7, 8-tetrahydro-6H-imidazo[4,5-e][1,4]diazepin-8-one. We have shown that in intramolecular cyclization of N-(2-hydroxyethyl)- or N-(2-chloroethyl)amides of 1-methyl-4-aminoimidazolyl-5-carboxylic acids it is not the corresponding tetrahydroimidazo[4,5-e][1,4]diazepin-8-ones which are formed but rather the isomeric 4-amino-5-(oxazolin-2-yl)imidazoles.

Novel synthesis of 4,5,7,8-tetrahydro-6H-imidazo[4,5-e]-[1,4]diazepine-5,8-dione. A cyclic xanthine homolog

The xanthine homolog 4,5,7,8-tetrahydro-6H-imidazo[4,5-e][1,4]diazepine-5,8-dione has been synthesized in four stages from cyanoacetamide.

Synthesis of halogen substituted imidazo[4,5-e][1,4]diazepine-5,8-diones. Cyclic homologs of methylxanthines

Possible routes for synthesis of 2-haloimidazo[4,5-e][1,4]diazepines are discussed. Conditions for chlorination differ for homologs of caffeine, theophylline, and theobromine. For the caffeine homolog, both the 2-chloroand 2,6,6-trichloro products are obtained depending on the synthetic conditions

Synthesis and some structural characteristics of caffeine and isocaffeine homologs

As a result of methylation and subsequent catalytic debenzylation, 1-benzylimidazo[4,5-e][1,4]diazepine was converted to the corresponding imidazo[5,4-e][1,4]diazepine. Thermodynamic parameters of inversion in isomeric imidazo[4,5-e]- and imidazo[5,4-e][1,4]diazepines were determined by dynamic 1HNMR. The total energy of the compounds being compared was calculated by molecular-mechanics methods.

Synthesis of crown-containing xanthine derivatives

A number of new derivatives of xanthine, hypoxanthine, theophylline, and theobromine containing crown-ether substituents at the nitrogen atoms of the imidazole or pyrimidine nucleus was synthesized. Translated from Khimiya Geterot-siklicheskikh