Chlorination of 1,3-dioxolan-4-ones

It is shown that the direction of chlorination of 1,3-dioxolan-4-ones in the presence of benzoyl peroxide is determined by the nature of the substituent at the 5-position of the ring. In this case a chloromethyl group, having a —I effect, promotes a selective replacement of hydrogen at the 2-position, while a methyl group mainly causes replacement of hydrogen at the 5-position.