Diversity‐Oriented Synthesis of Thiophenes Via Switchable Annulation of Ninhydrin‐Derived MBH Esters With α‐Enolic Dithioesters

We report a diversity-oriented synthesis of thiophene derivatives via a switchable annulation of ninhydrin-derived MBH esters with α-enolic dithioesters. By modulating the leaving groups of MBH esters (acetoxy vs. tert-butoxycarbonyloxy) and optimizing base-solvent combinations, three distinct thiophene scaffolds are selectively obtained in moderate to good yields. The regioselective synthesis is enabled by switchable S- or C-allylation pathways and subsequent divergent cyclization, providing a practical platform for accessing structurally diverse thiophene derivatives.