SYNTHESIS AND ISOMERIZATION OF OPTICAL ACTIVE 2-[(6, 7, 8, 9-TETRAHYDRO-5H-CYCLOHEPTA[b]PYRIDIN-9-YL)SULFINYL]-1H-BENZIMIDAZOLE ANALOGS

Abstract

Four stereoisomers, (Rs, 9R)-(+)-5, (Ss, 9R)-(-)-5, (Ss, 9S)-(-)-5 and (Rs, 9S)-(+)-5, were prepared from optically active (R)-(+)-3 and (S)-(-)-3, and their absolute structures were unambiguously determined by X-ray crystallographic analysis of (Ss, 9R)-(-)-5. Epimerization of the carbon bearing the sulfinyl group of 5 could be carried out with NaOCH₃. At the same time, it found that the stereochemistries of the sulfinyl group of (Rs, 9R)-(+)-5 and (Ss, 9S)-(-)-5 were spontaneously inverted in MeOH solution at room temperature.