Transition-metal chloride mediated addition reaction of diorganomagnesium to easily enolizable ketones

An alkylation to an easily enolizable ketone, such as β-tetralone, is difficult to perform with Grignard reagent (RMgX) or with diorganomagnesium (R2Mg), because a deprotonation to form a magnesium enolate occurs predominantly. To avoid the prior enolization, a complex reagent of a transition-metal salt and R2Mg was examined: A combination of R2Mg with iron(II) chloride (FeCl2) or ytterbium(III) chloride (YbCl3) gave a complex reagent that can realize a nucleophilic reaction to β-tetralone prior to the enolization. A combination of RMgX with these metal salts is inferior to a combination of R2Mg with them to obtain the nucleophilic complex reagent.