AbstractTheC2‐symmetrical chiral pyrrolidines2and3are of opposite helicity. The correspondingN‐acylnitroso dienophiles6and7react in good yield with cyclohexadiene, leading thereby with excellent diastereoisomeric excess to the expectedDiels‐Aldercycloadducts (seeScheme). The [2.2.2] bicyclic moieties of the major diastereoisomers9and11proved to be of opposite configuration, as expected. Their configuration is best explained by assuming the acylnitroso dienophile to be in the s‐cisconformation in the transition state, the approach of the diene beingendo(s