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Regioselectivities in Michael-type reactions of organoaluminium and organotitanium reagents with sterically hindered carbonyl compounds 1 and 5 concerning 1,2- versus 1,4-addition were determined. Throughout this investigation Me3Al/cat. Ni(acac)2 was found to be the most useful reagent for strongly hindered systems.

The conjugate methylation of α,β-unsaturated ketones with trimethylaluminium occurs smoothly in a very simple procedure under the catalytic effect of Cu1 salts. Scope and limitations of this process as well as the influence of solvent and catalyst on the kinetics were studied. In addition, the effect of chlorotrimethylsilane as an additive was investigated. Attack on the carbonyl group in 1,2-fashion could not be observed under the reaction conditions.

The effect of silanes as additives in the copper-catalyzed conjugate alkylation of enones by various organoaluminium reagents was investigated. TMSCl led to significant lower amounts of CuBr catalyst needed in the reaction of trimethylaluminium with enones, but was unsuccessful in the case of organoaluminium compounds of the formula Me 2 AlY (Y = Cl, OR). Me 2 AlOEt turned out to be a useful reagent for methylation without support of additives.

The 3-methoxy-2-cyclohexenones (I) react consecutively with LDA, methyl acrylate (II), and trimethylsilyl chloride (III) to form the ketene acetals (IV) which are desilylated and cyclized in the presence of SiO2 or TiCl4, yielding the bicyclic esters (V).