Unexpected SN2′-type addition–elimination reactions of 1-aryl-2,3-allenols with LiX. Synthesis and synthetic application of 1-aryl-3-halo-1,3-dienes

1-Aryl-3-halo-1,3-dienes were prepared from the sequential addition–elimination reaction of 1-aryl-2,3-allenols with LiX (X=Br, Cl) in HOAc in moderate to good yields. Here the aromatic substituent is crucial to this interesting transformation since no reaction was observed with 1-alkyl or perfluoroalkyl-2,3-allenols. The 1-aryl-3-halo-1,3-dienes prepared can be used as useful partners in Diels–Alder reactions with dienophiles leading to polycyclic quinone derivatives.