MgI2-catalyzed haloaldol reaction: a practical approach to (E)-β-iodovinyl-β′-hydroxyketones

Abstract

A novel generation of 1-iodo-3-siloxy-1,3-butadienes has been developed by reacting trimethylsilyl iodide (TMS-I) with α,β-unsaturated ketones in dichloromethane at 0 °C without the use of any catalyst. The halo aldol reaction of these butadiene intermediates with aldehydes was efficiently carried out by using magnesium iodide as the catalyst. Twelve β-iodo-α,β-unsaturated-β′-hydroxyketones (halo aldols) have been synthesized under the new condition with excellent geometric selectivity and good chemical yields (>80% chemical yields for 11 examples).