ASYMMETRIC CYCLOADDITIONS OF DIENES TO CHLORONITROSO COMPOUNDS DERIVED FROM CARBOHYDRATE KETONES - SYNTHESES OF (-)-PHYSOPERUVINE AND (-EPIBATIDINE())

An alpha-chloronitroso compound derived from D-xylose undergoes cycloa dditions with cyclic dienes to give bicyclic dihydrooxazines of high e nantiomeric purity; such adducts were used in a synthesis of (-)-physo peruvine and a formal synthesis of (+)-epibatidine, whilst a pseudoena ntiomeric chloronitroso compound is also available from L-sorbose.