Sulfonate and Sulfonamide Activated Olefins and Acetylenes in [4+2] Cycloaddition Reactions

Sulfonate and sulfonamide are electron withdrawing activators for both vinyl and acetylenic units. These vinyl (acyclic and cyclic) and acetylenic sulfonates and sulfonamides are versatile dienophiles in inter- and intramolecular Diels-Alder reactions, as well as dipolarophiles in 1,3-dipolar cycloadditions. Asymmetric versions of these cycloaddition reactions are also known. Further manipulation of the cycloaddition products afforded interesting compounds that are useful synthons and building blocks in natural product synthesis and asymmetric synthesis.