A general method for the generation of isobenzofuran intermediates is described. Lithiated aromatic acetals are converted to hydroxyacetals (A) which may be cyclized to isobenzofurans by mild acid treatment through the 1-hydroxyphthalans (B). The isobenzofurans generated in situ are trapped by a variety of dienophiles to provide the expected oxo-bicyclo adducts (C). The mass and 1Hmr spectra of B and C are discussed.
