Oxidative Rearrangement of 4-Hydroxy-2-cyclobutenone. A New Route to Highly Substituted Furanones from Squaric Acid

Article abstract of DOI:10.1021/jo00096a001

4-Hydroxy-2-cyclobutenones, which were obtained by the reaction of diethyl squarate with an organolithium, reacted with lead tetraacetate (to generate an oxy radical) affording 5-acetoxy-2(5H)-furanones and 5-alkylidene-2(5H)-furanones.This type of rearrangement was realized in a simple four-membered cyclic α-ketol but not in the corresponding five-membered ring.