Stereocontrolled synthesis of highly functionalized cyclohexenes. A short synthesis of a chorismic acid precursor

A convenient and mild thermal procedure has been developed for stereoselective 2+4-cycloadditions of electron-rich 1,2-dioxygenated olefins 7 to electron-deficient 3-sulfonyl-2-pyrone 6 allowing isolation of the structurally and stereochemically rich initial bicyclic adducts 8. These bicyclic adducts are shown to be useful building units as exemplified by a very short and high-yield preparation of a chorismic acid precursor.