Copper‐Catalyzed Dehydrative Cyclization of 1‐(2‐Hydroxyphenyl)propargyl Alcohols with P(O)H Compounds for the Synthesis of 2‐Phosphorylmethylbenzofurans

A tetrakis(acetonitrile)copper(I) hexafluorophosphate [Cu(MeCN)PF6]‐catalyzed dehydrative reaction of 1‐(2‐hydroxyphenyl)propargyl alcohols with diarylphosphine oxides has been developed to provide an efficient synthesis of phosphorylated benzofurans in good to high yields. In the presence of a catalytic amount of an organic base, a variety of H‐phosphonates and H‐phosphinates can also be employed as good substrates to produce the corresponding products in moderate yields. The reaction has significant economical and ecological advantages since the formation of a new C(sp3)–P bond and the benzofuran framework could both be achieved using an inexpensive copper catalyst with water produced as the sole by‐product. Some synthetic transformations of the product have also been demonstrated. magnified image