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TiCl4n-Bu4NX (X = I, Br, and Cl) Combination-Induced Coupling of α,β-Unsaturated Ketones with Aldehydes

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journal contribution
posted on 24.10.2001, 00:00 by Zhenfu Han, Shigeki Uehira, Hiroshi Shinokubo, Koichiro Oshima
A three-component coupling reaction between vinyl ketones, aldehydes, and halides has been developed with TiCl4n-Bu4NX combined reagents. Treatment of vinyl ketones with a TiCl4n-Bu4NI combination followed by an addition of a variety of aldehydes provides syn-α-iodomethyl-β-hydroxy ketones with high stereoselectivity. Methyltriphenylphosphonium iodide as well as n-Bu4NI acts efficiently as a halide source. The combination of TiCl4n-Bu4NBr provides the corresponding bromo compounds in good yields. syn-α-Chloromethyl-β-hydroxy ketones are obtained with the TiCl4n-Bu4NCl combination. A competitive experiment reveals that the order of relative reactivity of the combinations is TiCl4n-Bu4NI > TiCl4n-Bu4NBr > TiCl4n-Bu4NCl.

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