Directed ortho‐Metalation of O‐Aryl N,N‐Dialkylcarbamates: Methodology, Anionic ortho‐Fries Rearrangement, and Lateral Metalation

The directed ortho‐lithiation reactions of O‐aryl N,N‐dialkylcarbamates as well as O‐1‐naphthyl and O‐2‐naphthyl N,N‐dialkylcarbamates with sec‐butyllithium/tetramethylethylenediamine (sBuLi/TMEDA) followed by quenching with various electrophiles afford a range of polysubstituted aromatic compounds. If the solutions of the ortho‐lithiated carbamates are warmed to room temperature without the addition of external electrophiles, salicylamide and 1‐ and 2‐hydroxynaphthamide derivatives are formed through anionic ortho‐Fries rearrangements. The relative stabilities and reactivities of different O‐aryl N,N‐dialkylcarbamates were investigated. The lateral metalation of 2‐tolyl carbamates with lithium diisopropylamide (LDA) provides a route to benzo[b]furan‐2(3H)‐ones. Previously reported results are used in a comparison of seven O‐based directed metalation groups in reactions with several electrophiles. The described methodology is useful for the preparation of 1,2,3‐substituted aromatic compounds. The directed ortho‐lithiation (DoM) reactions of O‐aryl N,N‐dialkylcarbamates are studied comprehensively and provide, by quenching with various electrophiles, a range of polysubstituted aromatic compounds. In addition, anionic ortho‐Fries (AoF) rearrangements occur if the ortho‐lithiated carbamates are warmed to room temperature in the absence of an external electrophile.