Nickel-catalysed conjugate addition of trimethylaluminium to α,β-unsaturated ketones

Abstract

Nickel acetylacetonate brings about the conjugate addition of trimethylaluminium to α,β-unsaturated ketones. The yields of β- methylated ketones range from 30% to quantitative. At the same time, catalysis of 1,2-addition of trimethylaluminium to the α,β-unsaturated ketones also occurs (leading to allylic alcohols). The conjugate addition has been applied to 1,3-diphenylprop-2-en-1-one, cyclohex-2- en-1-one, 3-methylcyclohex-2-en-1-one, 1-acetylcyclohexene, pulegone, α-ionone, β-ionone and isophorone.     Iron(II), iron(III) and cobalt(III) acetylacetonates as catalysts for the conjugate addition give more varied products. Those from isophorone are most noteworthy.