| Abstract: | The diastereoselective [2+2] photocycloaddition of cyclohexenonecarboxylates containing various chiral auxiliaries to ethylene is described. The effect of the auxiliary, reaction temperature, and solvent on diastereoselectivity was examined. The (?)‐8‐(p‐methoxyphenyl)menthyl group was found to be the most effective chiral auxiliary. The photoreaction of (?)‐8‐(p‐methoxyphenyl)menthyl cyclohexenonecarboxylate in methylcyclohexane at ?78°C gave the corresponding bicyclo[4.2.0]octanone derivative in 81% diastereomeric excess (d.e.). The extent of diastereoselectivity was found to be closely related to the most stable π‐stack conformation of the starting cyclohexenones. Chirality 15:504–509, 2003. © 2003 Wiley‐Liss, Inc. |
