Abstract
The regiospecific 1,3-dipolar cycloaddition of 1,5-dihydropyrrol-2-one and arylnitrile oxides derivatives have been investigated. The asymmetric induction expected by the chiral centre of the 5-hydroxy-3-methyl-1,5dihydropyrrol-2-one derivatives was very effective, single diastereoisomers anti-3 was formed. The diastereoselectivity was linked to the destabilization of the syn transition state as a result of the electrostatic repulsion between the hydroxy group of the dihydropyrrol-2-one derivatives and the atom oxygen of the dipole.