[(CH2=CH)(2)Al(mu-OCH2CH2NMe2)](2): a vinylalane reagent suitable for conjugate additions to alpha,beta-unsaturated ketones

The reaction of AlCl3 with 2-dimethylaminoethanol in a 1:1 mole ratio yield s [Cl2Al(mu -OCH2CH2NMe2)](2) (1), which further reacts with two equivalent s of vinylmagnesium chloride to give the divinylalane [(CH2=CH)(2)Al(mu -OC H2CH2NMe2)](2) (2). Compound 2 was characterized by elemental analysis, H-1 , C-13, and Al-27 NMR spectra, mass spectrum and by X-ray structural analys is. Compound 2 was found to be a useful reagent for the transfer of a vinyl group to 1,3-diphenyl-2-propene-1 -one (trans-chalcone). The 1,4-addition product is formed regioselectively, both in a non-catalyzed as well as in a nickel-catalyzed reaction. (C) 2001 Elsevier Science Ltd. All rights reser ved.