2-HALO-2-CYCLOHEXENOLS FROM 6,6-DIHALOBICYCLO[3.1.0]HEXANES AND DIMETHYL-SULFOXIDE - STUDIES TOWARDS A NON-BASIC HYDROXIDE EQUIVALENT

A practical, high yielding, cheap and mild method for the synthesis of 2-halo-2-cycloalkenols, especially 2-bromo-2-cyclohexenol, is reporte d. Direct conversion from a variety of thermally labile n,n-dihalobicy clo[n-3.1.0]alkanes to 2-halo-2-cycloalkenols can be achieved without using silver salts by simple heating in DMSO. The intermediate 1,n-dih alocycloalkenes immediately undergo indirect allylic substitution with DMSO to yield the corresponding halocycloalkenols. A possible mechani sm for the substitution step comprises nucleophilic attack by DMSO fol lowed by a Pummerer rearrangement and hydrolytic decomposition. Kineti c and mechanistic experiments to verify the course of the reaction are presented.