NMR and AM1 Quantum Chemical Study of the Regioselectivity of the Reaction of 2-Hydroxyethyl Methacrylate with 3-Nitrophthalic Anhydride

Abstract

The reaction of 2-hydroxyethyl methacrylate with 3-nitrophthalic anhydride catalyzed with triethylamine results in the 3 : 1 mixture of two possible monoesters, the more populated one being that with the ester group in ortho position to the nitro group. The isomers were identified and quantified by 1H and 13C 1D and 2D techniques including APT, INEPT, superselective long-range (SSLR) INEPT, SSLR HHCR, COSY, NOESY, HETCOR and COLOC. Theoretical analysis was done on the model reaction of methanol with the anhydride using semiempirical AM1 quantum chemical calculations. The results indicate that the relative regioselectivity of the reaction is due to both the electron distribution in the anhydride molecule and hydrogen bonding in the stages immediately preceding the transition state.