Asymmetric ortholithiation of amides by conformationally mediated chiral memory: An enantioselective route to naphtho- and benzofuranones

An enantiomerically pure sulfinyl group ortho to an aromatic amide imposes absolute stereochemistry on the conformation of its Ar-CO axis. Sulfoxide-lithium exchange followed by addition to an aldehyde relays the chirality of the amide axis to the new hydroxyl-bearing stereogenic centre with good stereochemical fidelity. Lactonisation of the hydroxyamide gives naphthofuranones and benzofuranones, including the fungal metabolite isoochracein, but with substrate-dependent stereoselectivity.