The use of a Sila-Cope elimination afforded aZ,Z,Z trienamine derivative, direct synthetic precursor of (3Z,6Z,9Z)-3,6,9-nonadecatriene1, one of the pheromone components ofBoarmia selenaria. X-ray analysis of the tetrahydropyridinium salt13 leading to the dienic Vinyl silane14 allowed the determination of the relative configurations of the tetrahydropyridine intermediates7,8,9 and12. © 1990 Pergamon Press plc.