ENANTIOSPECIFIC PREPARATION OF [(2R, 6S)-ENDO]-5-AZA-1,10,10-TRIMETHYL-3-OXATRICYCLO[5.2.1.0(2,6)]DECAN-4-ONE BY A NITRENE-MEDIATED ROUTE FROM [(1S)-ENDO]-(-)-BORNEOL AND ITS UTILITY AS A CHIRAL AUXILIARY IN SOME ASYMMETRIC TRANSFORMATIONS

Attempted chiral aziridination of styrene by addition of optically-active alkoxycarbonylnitrene 5 derived from [(1s)-endo]-(-)-bornyl p-nitrobenzenesulphonoxycarbonate 4 is reported. No measurable asymmetric induction is observed under the various conditions employed, but in the absence of alkene, a tricyclic oxazolidin-2-one 8 is formed to which preparatively simpler access can be gained by thermal decomposition of azidoformate 7, either in 1,1,2,2-tetrachloroethane (50%) or by spray pyrolysis (58%). The oxazolidin-2-one 8 is demonstrated to be a successful chiral auxiliary by contemporary standards in a variety of asymmetric transformations, including alkylation, acylation, and aldol reactions for which high levels of asymmetric induction are observed. Diethylaluminium chloride-catalysed Diels-Alder reactions exhibit poorer selectivity except for the cinnamoyl derivative 23 which is stereospecific.