Silver/Scandium-Cocatalyzed Bicyclization of β-Alkynyl Ketones Leading to Benzo[c]xanthenes and Naphtho[1,2-b]benzofurans.

Author(s) Chen, K.; Liu, S.; Wang, D.; Hao, W.J.; Zhou, P.; Tu, S.J.; Jiang, B.
Journal J Org Chem
Date Published 2017 Nov 03

The combination of AgTFA and Sc(OTf)3 enables the bimetallic synergistic catalysis of β-alkynyl ketones and para-quinone methides (p-QMs), allowing direct synthesis of 17 examples of benzo[c]xanthenes with generally good yields through a benzannulation/1,6-addition/cyclization sequence. Exchanging p-QMs for quinone imine ketal resulted in 10 examples of tetracyclic naphtho[1,2-b]benzofurans via a similar benzannulation/1,4-addition/cyclization cascade. During these reaction processes, AgTFA and Sc(OTf)3 could be perfectly compatible, together with the realization of C(sp3)-H functionalization adjacent to carbonyl group on the β-alkynyl ketone unit.

DOI 10.1021/acs.joc.7b02134
ISSN 1520-6904
Citation J Org Chem. 2017;82(21):1152411530.

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