Studies on Pheromones of Female Eri-Silk Moth, I. Preparation of C₆-C₁₁ 2-Alkenyl Triphenyiphosphonium Bromides

proposed to prepare tkese subs£ances and in this paper describe syntheses of the tieled compounds, which are intermediate in the syntheses. The syntheses were carried out in the conventional way (scheme)4) : Propargyloxy tetrahydropyran (!) was condensed with alkyl bromides (2) using the classical Na in liq. ammoRia method to give alkynyloxy tetrahydropyran (3), which were then hydrolyzed to the correspoRding free alcohols (4). These were converted either to the (Z)-alkenols (5(Z)) by hydrogenation over Lind}ar catalyse5) or to the (E)-alkenols (5(E)) by treating with lithium tetrahydroaluminate according to tlte Rossi's procedure.6) Eack product was converted to the corresponding bromides (6(Z) or 6(E)) on treatment with 47% HBr aq, and these were then converted to the corresponding triphenylphosphonium bromides (7). The lntermediate compounds, 3,4,5 and 6, were characterized by IRand NMRspectral analyses. As far as observed from spectral data, allylic rearrangement product could not be detected in 6, aRd, however, the stereoselectivity of P, r-double bond seems to be not distinctly retained in the brominatioR as revealed from IR-spectra. The final products 7 were at any rate obtained as analysis-pure substances. Their NMR-analyses were also satisfactorily coincident to the structures, although the geometrical purity can not be critically detected. These products were, however, used for tke further syntheses, because it was not absolutely necessary to use the geometrically absolutely pure substances for our present purpose.3)