Synthesis of C3-Substituted 1-Indenones Enabled by CuCl/Brønsted Acid Cooperative Catalysis
Jiacheng Yin1, Yansheng Wei1, Yun Li1
1State Key Laboratory of Natural Product Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 Gansu, P. R. China.
Abstract:
A cooperative CuCl/Brønsted acid catalytic system has been developed to enable divergent C3-functionalization of o-alkynylbenzaldehydes through a key O-5-exo-dig cyclization pathway. The resulting allylic carbocation intermediates can be efficiently intercepted by either styrenes or alcohols, affording 3-styryl-1-indenones and 3-alkoxy-1-indenones, respectively, with complete regioselectivity. The exocyclic styryl moiety serves as a synthetically versatile handle for late-stage diversification of indanocine-type scaffolds. This operationally simple method employs inexpensive CuCl as the sole metal catalyst under mild conditions, furnishing 35 examples in yields of up to 98%.
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