3,4-Disubstituted Δ3-pyrrolin-2-ones were prepared in high yields via 5-tosyl-Δ3-pyrrolin-2-ones (4) startingfrom 2-tosylpyrroles regioselectively. The compounds 4 were found to be useful intermediates for the preparation of a variety of Δ3-pyrrolin-2-one derivatives. The reactions of 4 with various nucleophiles and active methylene compounds bearing an appropriate leaving group are described.
Tosyl group of 3,4-disubstituted 2-tosylpyrroles easily rearranged from 2- to 5-position by treatment with TFA. The ratio of the regioisomers at equilibrium was definitely influenced by the bulkiness of the substituent at 3-position of the starting 2-tosylpyrroles.