Base-Promoted Cascade Double Heteroannulation of 2-Hydroxychalcones with Elemental Sulfur: An Approach to 2-Aryl-9λ ⁴ -benzo[ d ][1,2]oxathiolo[2,3- b ][1,2]oxathioles

][1,2]oxathioles via a base-promoted cascade reaction of 2-hydroxychalcones and elemental sulfur under simple heating conditions. This innovative one-pot process provides a straightforward synthetic platform for the concomitant formation of one C═S bond, two S-O bonds, and two fused heterocyclic rings with excellent atom and step efficiency. Simple, inexpensive, and readily available starting materials, operational simplicity, acceptable functional group tolerance, scalability, synthetically useful yields, and attractive product structures are some other highlighted features of this transformation. Dedicated to Prof. Habib Firouzabadi on the occasion of his 83th birthday.