Efficient AgOTf or Ph3PAuCl-AgSbF6 catalyzed cyclization of 1-hydroxy-2-alkynylallylphosphonates/2-alkynylallyl alcohols to 2-furylphosphonates/2,3,5-trisubstituted furans

The reaction of 1-hydroxy-2-alkynylallylphosphonates, synthesized by the addition of the corresponding phosphites to 2-alkynylcinnamaldehydes, under AgOTf or Ph3PAuCl-AgSbF6 catalyzed cycloisomerization afforded 2-furylphosphonates in good to excellent yields. These cyclization reactions were compared with those of 2-alkynylallyl alcohols that led to multisubstituted furans.