Der Mechanismus der Addition von Nucleophilen an Alkinderivate mit Push‐pull‐Gruppen

The mechanism of the addition of nucleophiles to alkyne‐derivatives 1 having both push‐ and pull‐groups yielding Michael‐adducts is investigated. The rate of the second‐orderreaction increases (a) with increasing nucleophilic character of the amine and alcohol respectively, (b) with increasing electrophilic character of the alkyne‐derivatives 1, and (c) with increasing solvent polarity. These results support as rate‐determining step an attack of the nucleophile at C(3) of the alkyne‐derivatives.