NHC-Organocatalyzed CAr -O Bond Cleavage: Mild Access to 2-Hydroxybenzophenones
Daniel Janssen-Müller1, Santanu Singha1, Fabian Lied1
1Westfälische Wilhelms-Universität Münster, Organisch-Chemisches Institut, Corrensstrasse 40, 48149, Münster, Germany.
Abstract:
A Truce-Smiles rearrangement of acyl-anion equivalents generated by N-heterocyclic carbene (NHC) catalysis has been achieved. The developed method includes CAr -O, CAr -S, or CAr -N bond cleavage for the formation of a CAr -C bond and enables access to 2-hydroxybenzophenones, an important structural motif that is present in several bioactive natural products. By utilizing this procedure, the alkaloid taxilamine was synthesized in three steps. DFT calculations and control experiments support a classical SN Ar mechanism with a catalyst-bound Meisenheimer-type intermediate. The method features mild reaction conditions, excellent functional-group tolerance, and a broad substrate scope, including various classes of (hetero)arenes.
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