A novel and efficient method to prepare 3-(hetero)aryl-1-propynes and its application to the stereoselective synthesis of (2E,4E)-N-(2-methylpropyl)-6-(2-methylpropyl)-6-(2-thienyl)-2,4-hexadienamide, piperovatine and (E)-N-(2-methylpropyl)-6-(4-methoxyphenyl)-4-hexyn-2-enamide