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The concise and efficient one-pot synthesis of 2-Rnaphtho [2,3-b]thiophene-4,9-diones from 2-bromo-1,4-naphthoquinone and alkynes has been developed. The reaction proceeds through the formation of 2-(R-ethynyl)-1,4-naphthoquinones, which undergo transformation with Na 2 S 2 O 3 to 2-R-naphtho[2,3b]thiophene-4,9-diones via C−H sulfuration, accompanied by the formation of the aromatic Bunte salt, followed by its air oxidation and 5-endo-dig cyclization. The protocol is characterized by simplicity, good tolerance for functional groups, relatively mild conditions, and commercially available starting compounds.

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