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
Abstract
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.