Results Materials.-The mixture of endo-and exoacetates I-OAc and 11-OAc is readily available from the Diels-Alder reaction between cyclopentadiene and vinyl a~ etate.~ The exo-endo-4a, 8a-fusion of the two bicycloheptane nuclei was deduced by Solo-way4 in an excellent analysis of the stereochemistry of fused norcamphane systems. The necessary plausible assumption that the configuration of the carbon skeleton of I and I1 is identical ...