Palladium-catalyzed [4+2] and [6+2] dipolar cycloadditions for the construction of benzo[d]isothiazole 1,1-dioxide fused 1,3-oxazinanes and 1,3-oxazocanes

The Pd-catalyzed dipolar cycloaddition represents a significant synthetic strategy for the construction of useful heterocyclic com-pounds. This study developed the dipolar [4+2] and [6+2] cycloaddition reactions of benzo[d]isothiazole 1,1-dioxides (BDs) leading to the synthesis of BD-fused 1,3-oxazinane and 1,3-oxazocane derivatives, respectively. In particular, the synthesis of BD-fused 1,3-oxazinanes demonstrated regio- and enantioselective characteristics, resulting in products with good yields, enantioselectivity and regioselectivity (if applicable). Furthermore, the [6+2] cycloaddition reaction developed in this work represented the first strat-egy for the synthesis of medium-sized ring compounds based on BDs.