Olga V. Denisko

Novel and convenient routes to substituted pyrroles and imidazoles

Abstract S-Melhyl N-(benzotriazol-1-ylmethyl)thioimidate 6 is obtained by lithiation of the corresponding N-(benzotriazol-1-ylmelhyl) thioamide 5 and subsequent reaction with methyl iodide. Derivative 6 undergoes [2 + 3] cycloaddition reactions with α,β-unsaturated -esters, -ketones and -nitriles, and vinylpyridines which are followed by elimination of benzotriazole and the thioalkoxy group, to give 2,3,4-trisubstituted pyrroles. Lithiaiion of 6 followed by reactions with imines gives cyclized 4,5-dihydroimidazoles 14 which upon further treatment with ZnBr2 or direct refluxing in toluene yield the 1,25-trisubstituted imidazoles 15 in good yields.

Designing efficient synthetic routes to polyfunctionality

Benzotriazole-mediated methodology was successfully applied for the preparation of many classes of polyfunctional organic compounds.

Synthetic Elaboration of N-Substituents in Thioamides

Abstract N -(Benzotriazol-1-ylmethyl)arylthioamides, readily prepared from arylthioamides, formaldehyde and benzotriazole, undergo lithiation followed by reactions with alkyl halides, aldehydes and ketones to introduce the expected N -substituents into the N -methylene group. Subsequent displacements of the benzotriazolyl group by Grignard reagents, alkoxide or thioalkoxide anions provide general access to a wide variety of N -substituted thioamides in good yields.

NEW PODANDS WITH TERMINAL CHROMOGENIC MOIETIES DERIVED FROM FORMAZANS

Synthesis of several new podands, bearing various terminal chromophoric functions of formazan (9–11), verdazyl (18–20) and verdazylium salt (21–23) types and having a different length of oligooxyethylene bridge between chromophoric units, is developed. Calculated (Alchemy-2000) and found (EPR data) distances between spin centers in bis-radicals 18–20 correlate well. Such spin-labeled species could be good models for the EPR study of host–guest interactions involving ethylene glycol-based podands.