The 5-hydroperoxyfuran-2 (5H)-ones 3 are synthesized by acid hydrolysis of the dihydrofurans 1 which are prepared in one-pot procedure by reaction of the corresponding furans 4 with singlet oxygen and methanol. The synthetic method has a wide range of applicability; however, compounds 3 unsubstituted at C-4 cannot be prepared since the corresponding dihydrofurans 1 are not formed. The furan-2 (5H)-one skeleton appears in ...