TiCl4-n-Bu4NX (X = I, Br, and Cl) combination-induced coupling of alpha,beta-unsaturated ketones with aldehydes. |
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| Authors: | Z Han S Uehira H Shinokubo K Oshima |
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| Institution: | Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan. |
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| Abstract: | A three-component coupling reaction between vinyl ketones, aldehydes, and halides has been developed with TiCl(4)-n-Bu(4)NX combined reagents. Treatment of vinyl ketones with a TiCl(4)-n-Bu(4)NI combination followed by an addition of a variety of aldehydes provides syn-alpha-iodomethyl-beta-hydroxy ketones with high stereoselectivity. Methyltriphenylphosphonium iodide as well as n-Bu(4)NI acts efficiently as a halide source. The combination of TiCl(4)-n-Bu(4)NBr provides the corresponding bromo compounds in good yields. syn-alpha-Chloromethyl-beta-hydroxy ketones are obtained with the TiCl(4)-n-Bu(4)NCl combination. A competitive experiment reveals that the order of relative reactivity of the combinations is TiCl(4)-n-Bu(4)NI > TiCl(4)-n-Bu(4)NBr > TiCl(4)-n-Bu(4)NCl. |
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