A serendipitous
synthesis of N-substituted 2-amino-2′-hydroxy-1,1′-biaryls
through an aryne annulation with indolyl β-ketonitrile/ester
in a cascade manner is demonstrated. The reaction sequence involves
benzyne-mediated [2 + 2] Stoltz-type cycloaddition–cleavage
and intramolecular Michael addition followed by C–N bond cleavage
under transition-metal-free reaction conditions. Interestingly, while
[4 + 2] Diels–Alder reaction is a possible pathway, no traces
of the regioisomer was isolated.
Aryne insertion reaction with 2-aroyl malonates/ cyanoesters lead to the formation of diarylmethane or chromones depending on the substitution on the aryne ring. Presence of electronegative atom at ortho position...
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