Directed ortho-Metalation of O-Aryl N,N-Dialkylcarbamates: Methodology, Anionic ortho-Fries Rearrangement, and Lateral Metalation
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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.
Research Subject Categories::NATURAL SCIENCES::Chemistry::Organic chemistry::Organic synthesis , Ortho‐lithiation reactions , O‐1‐naphthyl and O‐2‐naphthyl N,N‐dialkylcarbamates , Polysubstituted aromatic compounds , 2‐tolyl carbamates
Miah, M. J., [Et...al] (2018). Directed ortho‐Metalation of O‐Aryl N, N‐Dialkylcarbamates: Methodology, Anionic ortho‐Fries Rearrangement, and Lateral Metalation. European Journal of Organic Chemistry, 2018(4), 440-446.