The use of a Sila-Cope elimination afforded a Z,Z,Z trienamine derivative, direct synthetic precursor of (3Z,6Z,9Z)-3,6,9_nonadecatriene 1, one of the pheromone components of Bourmia selenaria. X-ray analysis of the tetrahydropyridinium salt 13 leading to the dienic vinyl silane 14 allowed the determination of the relative configurations of the tetrahydropyridine intermediates 7,8,9 and 12.
Our continuing studies using 2-alkyl-1,2,5,6-tetrahydropyridines as precursors of dienic derivatives led to the syntheses of various dienic pheromones. 1 In particular, we have demonstrated that 1,4 Z,E and Z,Z dienes can be obtained with a good stereoselectivity via the Sila-Hofmann and the Sila-Cope eliminations.2 Further scope of these reactions including the synthesis of (32,6Z, 9Z)-3,6,9-nonadecatriene 1, a component of the sex pheromonal system of the giant looper, Boarmiu selenaria,3 and also some study concerning the stereochemical implication of these eliminations are presented in this report.
/=/\r=W'9 3 6 9 reflexions I > 3a(I)). Structure solved by Patterson-Fourier methods and refined by full matrix leastsquares. Hydrogen atoms were refined with an isotropic thermal factor equivalent to that of the bonded atom (+20%). Final R factor : 0.041. Atomic coordinates, distances and angles were deposited with the Crystallographic Cambridge Data Bank. 8. Capillary column (25 m x 0.22 mm), CPSil.SCB. Chrompac, temperature 17O"C to 25O'C (2"C per min.). 9. We thank Prof. H.J. Bestmann and Dr. 0. Vostrowsky for sending us copies of the mass and NMR spectra of pheromone 1.