Base-Mediated Annulation\nof <i>ortho</i>-Iminophenols and <i>ortho</i>-Vinylphenols\nwith MBH Carbonates\nof Isatins: Straightforward Access to Dihydrobenzofuran and Benzofuran\nDerivatives

We\nhave developed a convenient synthetic protocol for efficient\nconstruction of significant dihydrobenzofuran and benzofuran scaffolds\nby Lewis base-mediated annulation reaction <i>ortho</i>-iminophenols\nand <i>ortho</i>-vinylphenols with MBH carbonates of isatins\nunder mild and metal-free conditions. The selective generation of\ndifferent kinds of dihydrobenzofuran and benzofuran derivatives was\nsuccessfully achieved by employing different substituted isatin-derived\nMBH carbonates with <i>ortho</i>-<i>N</i>-tosyliminophenols\nand <i>ortho</i>-vinylphenols. The features included broad\nsubstrate scopes, excellent functional group compatibility, high molecular\ndiversity, and atomic economy.