Harribert Neh

Copper-catalyzed conjugate addition of trialkylaluminium to α,β-unsaturated carbonyl compounds

Abstract The Michael-type reaction of copper-catalyzed trialkylaluminium reagents with α,β-unsaturated carbonyl compounds is a useful and simple procedure for the transfer of hydrocarbon substituents. The scope of this process and the effect of chlorotrimethylsilane as additive were investigated. Preparatively useful results were generally obtained for enones even with higher organoaluminium reagents, whereas the reaction with α,β-unsaturated aldehydes was limited to the use of trimethylaluminium.

Nickel catalysed 1,4-addition of organotitanium ate complexes to sterically hindered enones

Abstract The 1,4-addition of organotitanium ate complexes to enones by nickel catalysis is reported. With a methyltitanium ate complex good yields of conjugate addition to sterically hindered enones are achieved. Phenyltitanium ate complexes react with less sterically encumbered enones to the 1,4-addition products in moderate to high yields.

Studies towards a total synthesis of the antiprogestine onapristone

Abstract Starting from the readily available Eder-Hajosh ketone 2 a stereoselective method for synthesis of arylated hydrindenone 14 was developed. One pot Li/NH 3 reduction and trapping of the generated enolate with activated Michael acceptor gave a properly substituted BCD-ring precursor 22 . Attempted B ring closure with the model compound 22 failed under various conditions.

The role of silanes on the copper-catalyzed conjugate alkylation of enones by organoaluminium reagents

Abstract 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.