The course of condensation reactions of alkyne carboxylic acid orthoamides 17a,b is strongly influenced by the nature of the solvent used. Non-acidic or at least low-acidic polar solvents possessing high ET(30) values are best suited for these reactions. The condensation reactions can also be catalyzed by boric acid esters. Bicyclic boric acid esters such as 25 and 27, derived from trioles, are the most effective catalysts. The use of these catalysts allows to prepare conveniently 5,5-bis(dimethylamino)butadienes 18a,b from the acetophenones 16a,b and the orthoamides 17a,b. (c) 2007 Elsevier B.V. All rights reserved.