Asymmetric induction of four chiral centers by hetero Diels‐Alder reaction of a chiral nitroso dienophile

The Diels‐Alder reaction of cis ‐5,6‐diacetoxy‐1,3‐cyclohexadiene ( 1 ), which has a meso configuration, with the chiral nitroso dienophile 2 occurs with induction of four asymmetric centers in very high optical yield (ee = 94%) and leads to the dihydro oxazine 3 (89%). The influence of the reaction temperature on the asymmetric induction was investigated and the absolute configuration of the product determined. Reductive cleavage of the N O bond of 3 presents a simple route to enantiomerically pure derivatives of (1 R )‐conduramine A1 (82%).