Nucleophilic Addition of Enols and Enamines to α,β-Unsaturated Acyl Azoliums: Mechanistic Studies
Angew.Chem.Int.Ed., 2012, 51, 5234-5238 published on 13.04.2012
1,4 but not 1,2! The reactivity of 1 towards different nucleophiles (deprotonated β-diketones, enamines, and malonodinitrile) was investigated by NMR and kinetic experiments. These investigations proved that CC bond formation occurs by a Michael-type 1,4-addition and not by a 1,2-addition and subsequent [3,3]-sigmatropic rearrangement. The first X-ray structure of an α,β-unsaturated acyl azolium salt (1) is also presented.