The thermal reaction of 3-[(1S)-2-alkoxy-1-apocamphanecarbonyl]-2-oxazolones (21a-c) with dialkyl azodicarboxylates (9) results in exclusive formation of [4+ 2] type cycloadducts (22 and 23) with moderate levels of diastereofacial selection (up to 72% de). The diastereomers thus obtained were readily purified and subsequent treatment with acidic methanol followed by removal of the auxiliary with LiBH 4MeOH (1: 2) gave optically pure ...