Diastereoselective [3+2]-photocycloaddition of chiral 1,4-naphthalenedicarboxylic esters to alkenes

[3+2]-Photocycloaddition of di-(-)-menthyl, di-(-)-8-phenylmenthyl, and di-(-)-bornyl 1,4-naphthalenedicarboxylates to alkenes, such as isobutene, styrene, and alpha-methylstyrene, proceeded with diastereoselectivity, up to 62% diastereomeric excess (de), largely depending on the concavity of the auxiliary, steric bulk of the substituents of the alkenes, and reaction temperature. The de values remarkably increased with decrease of the reaction temperature, and linear dependence of In(diastereomeric ratio) on 1/T was observed. (C) 1999 Elsevier Science Ltd. All rights reserved.