Directed ortho-Metalation of Aryl Amides, O-Carbamates, and Methoxymethoxy Systems: Directed Metalation Group Competition and Cooperation

A systematic study on the competitive metalation of derivatives containing four directed metalation groups (DMGs), namely, Cl, OMe, methoxymethoxy (OMOM), and CONEt2, in comparison with the OCONEt2 DMG is described. In addition, the anionic ortho-Fries (AoF) rearrangement, the double metalation-electrophile quench of 1,2- and 1,4-O-carbamates, and iterative metalation procedures are presented. The results provide new methodologies for the synthesis of contiguously functionalized 1,2,3- and 1,2,3,4-substituted aromatic derivatives of difficult accessibility and potential broad utility. A comparison of the present methodology with previously developed routes is provided for selected examples with emphasis on such substituted compounds.