A direct route to conjugated enediynes from dipropargylic sulfones by a modified one-flask Ramberg–Bäcklund reaction

The reaction of dipropargylic sulfones with dibromodifluoromethane in the presence of alumina-supported KOH in dichloromethane solution results in facile rearrangement affording the corresponding conjugated linear and cyclic enediynes in good yields. This result shows that the direct transformation of α- and α′-hydrogen bearing sulfones assembles enediyne units without resorting to the prior preparation of the α-halo sulfone precursors in a separate step.