engleski

Regiospecific Synthesis and Structural Study of some Trifluoromethyl Substituted Dibenzosemibullvelenes

Preparation of the regiospecifically trifluoromethyl substituted dibenzosemibullvalenes 3 and 5 is described. An unequivocal proof of chirality of 3 and 5 was obtained by enrichment of their enantiomers using liquid chromatography on triacetyl- or tribenzoylcellulose. The stereostructure of compounds 3 to 5 was prooved by their 1H NMR spectra and confirmed by x-ray crystallographyc analysis. The geometrical data from x-ray structural analysis showed that five-membered rings involved in skeleton of 3 and 5 adopt flattened envelope conformations. These results indicate also a significant substituent-induced bond length asymmetry in the cyclopropane ring of 3 and 5.

dibenzobarrelene; dibenzosemibullvalene; enantioselective chromatography; trifluoromethylation; photochemical rearrangement; x-ray crystal structures

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