Palladium-Catalyzed Cross-Couplings of Unsaturated Halides Bearing Relatively Acidic Hydrogen Atoms with Organozinc Reagents

Abstract

A wide range of polyfunctional aryl, heteroaryl, alkyl, and benzylic zinc reagents were coupled with unsaturated aryl halides bearing an acidic NH or OH proton, using palladium(II) acetate (1 mol%), and S-Phos (2 mol%) as catalyst without the need of protecting groups.

Key words

palladium catalysis - cross-coupling - functionalized zinc reagents - polyfunctional biaryls

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9

Typical pK _a values (in DMSO) for anilines range between 20-30; for a comprehensive compilation of pK _a data see http://www.chem.wisc.edu/areas/reich/pkatable/index.htm and references cited therein.

12

Our experiments indicate a relative kinetic basicity of zinc reagents: arylzinc halide > alkylzinc halide > benzylic zinc halide. For further experimental details, see ref. 7.