title: Chiral lithium amide base-mediated rearrangement of meso-cyclohexene oxides: asymmetric synthesis of amino- and aziridinocyclohexenols.
abstract: Two different chiral lithium amide base routes for the synthesis of amino- and aziridino-containing cyclohexenols have been explored. The first strategy involved the diastereoselective preparation of novel meso-aziridinocyclohexene oxides and their subsequent enantioselective rearrangement using chiral bases. In this approach, the diphenylphosphinoyl nitrogen protecting group proved optimal and aziridinocyclohexenols of 47-68% ee were obtained. Of particular note was the smooth rearrangement of the epoxide to an allylic alcohol in the presence of an aziridine: under optimised chiral base conditions, the aziridine remained essentially unaffected. A second more straightforward strategy for introduction of an amino functionality was also investigated: (1S,4R,5S)- and (1R,4R,5S)-4,5-bis(tert-butyldimethylsilyloxy)cyclohex-2-enols, readily prepared in > 95% ee using a chiral base approach, were subjected to Mitsunobu substitution using a sulfonamide and Overman rearrangement.
authors.affiliation: Department of Chemistry, University of York, Heslington, York, UK YO10 5DD. paob1@york.ac.uk
authors.forename: Peter
authors.initials: P
authors.lastname: O'Brien
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Pilgram