ORGN 301

A highly efficient method is presented for three-and four-component reactions to prepare polyfunctional sulfones, sulfonic esters and sulfonamides, in one-pot.The three-component reaction relies on an ene-reaction of silyl enol ethers of esters, ketones and allylsilanes with sulfur dioxide. In the four-component reaction SO₂ undergoes first a hetero-Diels-Alder addition with a 1,3-diene before oxyallylation of silyl enol ethers or allylsilanes. The key intermediate in both reactions is a silyl sulfinate which can react with a wide variety of different electrophiles to provide either polyfunctional sulfones, sulfonic esters or sulfonamides. Since those molecules are well known for their potent biological activities the method should have broad applications in medicinal chemistry.