Nickel-catalyzed cross-coupling of chromene acetals and boronic acids.

Thomas J A Graham, Abigail G Doyle

Index: Org. Lett. 6th ed., 14 , 1616-1619, (2012)

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Abstract

A modular and highly efficient protocol for the synthesis of 2-aryl- and heteroaryl-2H-chromenes is described. Under base-free conditions, readily accessible 2-ethoxy-2H-chromenes undergo C(sp(3))-O activation and C(sp(3))-C bond formation in the presence of an inexpensive nickel catalyst and boronic acids. This new strategy enables broad access to 2-substituted-2H-chromenes and has been applied to the late-stage incorporation of complex molecules, including the pharmaceuticals loratidine and indomethacin methyl ester.