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2.9.2.1.4 Chromium-Catalyzed Alkenylation (Nozaki–Hiyama–Kishi Reaction)

DOI: 10.1055/sos-SD-202-00221

Kauffman, M. C.; Walsh, P. J.Science of Synthesis: Stereoselective Synthesis, (20112482.

Another approach to the alkenylation of carbonyl compounds is the NozakiHiyamaKishi (NHK) reaction, which involves use of a chromium catalyst to deliver a variety of organic groups, including alkenyl groups, to carbonyl compounds. An advantage of the NozakiHiyamaKishi reaction is that the starting material is an alkenyl halide, as in the Grignard reaction. Unlike Grignard reagents, the organochromium intermediates in the NozakiHiyamaKishi reaction are very selective for aldehydes and are compatible with most functional groups, making the NozakiHiyamaKishi reaction a popular choice for complex molecule synthesis. In addition to the chromium catalyst, the NozakiHiyamaKishi reaction employs a stoichiometric reducing agent such as manganese(0) and chlorotrimethylsilane or dichlorobis(cyclopentadienyl)zirconium(IV) (zirconocene dichloride) to remove the alkoxide product from the chromium catalyst, permitting turnover.[‌147‌,‌148‌] In the case of alkenyl iodides, a nickel cocatalyst [e.g., nickel(II) chloride2,9-dimethylphenanthroline, NiCl2DMP] is needed for the activation of the CI bond.

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