Treatment of various substituted allenols with indium(III) halide in benzene gave (Z)- or (E)-2-halo-1,3-dienes in moderate to good yields. In most cases, (2Z)-halo-1,3-dienes were obtained as major products.
allenol - indium(III) halide - 2-halo-1,3-diene - SN2′ reaction