Starting from (+)-or (-)-camphor, the antipodal alcohols 14 and 18, respectively, have been prepared; the corresponding acrylates 15 and 19 underwent TiCl,(i-PrO)2-mediated Diel.vAlder additions to cyclopentadiene to give adducts 20a and 22a respectively, with 95% endo-and 99.2% n-face selectivities. Adduct 22a was converted to enantiomerically pure norbornenone 26. Addition of 1,3-butadiene to acrylate 15 in the presence of TiC1, Introduction. ~ Given the fundamental role of the Diels-Alder reaction in organic synthesis [I], it is without question that the control of its absolute topicity constitutes a topic of pressing importance. It was, however, not until recently that substantial effort has been devoted to and hence significant progress achieved in this area [2].As an extension of a preliminary communication [3], we report here in detail the first successful surmounting of the threshold of 99 % face-stereodifferentiation in the Diels-Alder process. Its value is illustrated by application to the syntheses of enantiomerically pure building blocks and also of a natural product. The starting point for this work was the encouraging chiral induction observed with Lewis-acid-promoted ene-type cyclizations (1h2) [4] and [4+2] cycloadditions (3-4) [5] of 8-phenylmenthyl enoates