An expedient one-pot sequential three-component reaction for the stereoselective synthesis of functionalized spiro-sulfamidate imine fused δ-lactone scaffold

A convenient one-pot three-component transformation between 4-aryl-5H-1,2,3-oxathiazole-2,2-dioxides, trans-β-aryl/alkyl-substituted acroleins and paraformaldehyde in CH2Cl2 at room temperature in the presence of commercially available l-proline and DBU as the organocatalysts has been successfully realized for the first time via a Michael-condensation-hemiacetalization sequence process. The resulting functionalized spiro-sulfamidate imine fused δ-lactone scaffolds were obtained via in situ oxidation of spiro-δ-lactols by PCC in good to excellent overall yields and moderate to good diastereomeric ratio (up to ⩽5:1 dr). Moreover, a synthetically useful intermediate trans–cis-β-amino-α-azido compound has been successfully achieved through our procedure.