Lanthanide triflate-catalyzed preparation of beta,beta-difluorohomopropargyl alcohols in aqueous media. Application to the synthesis of 4,4-difluoroisochromans

An indium-mediated Barbier-type reaction of difluoropropargyl bromide with several aldehydes in aqueous media was enhanced by a catalytic amount of a lanthanide triflate (5 mol %). The reaction gave the corresponding beta,beta-difluorohomopropargyl alcohols with high regioselectivity. The 2 + 2 + 2] alkyne cyclotrimerization of beta,beta-difluorohomopropargyl alcohols with monosubstituted acetylenes produced 4,4-difluoroisochromans in good yields with moderate regioselectivity.