INSECT PHEROMONES AND THEIR ANALOGS. XXIII. SYNTHESIS OF (7R,8S)-(+)-cis-2-METHYL-7,8-EPOXYOCTADECANE - THE SEX PHEROMONE OF Porthetria dispar

Article abstract of DOI:10.1007/BF00598087

A four-stage asymmetric synthesis of (+)-disparlure <(7R,8S)-(+)-cis-methyl-7,8-epoxyoctadecane (V)> has been effected from 8-methylnon-2Z-en-1-ol (I), obtained by the carboalumination of acetylene with tris(5-methylhexyl)aluminum using the Sharpless reaction.The asymmetric epoxidation of (I), (Ar, mol. sieve A, (+)-DET, (iOPr)4Ti, T-BuOOH, -15 deg C, 20h; H2O, 1h, NaOH, -7 deg C, 30 min) gave 8-methyl-2S,3R-epoxynonan-1-ol (II), which was oxidized (kieselguhr-CrO3-Py, 0 deg C, 2h; 25 deg C, 2h) to 8-methyl-2S,3R-epoxynonan-1-al (III).The coupling of (III) with n-C8H17CH=PPh3 (-78 deg C, 1h; 25 deg C, 15h) gave 2-methyl-7R,8S-epoxy-octadec-9Z-ene (IV), the hydrogenation (H2/5percentPd-C, 25 deg C, 5 days) of which led to (V) in admixture with an isomerzation product.Compound (V) was isolated by HPLC.Substance, yield, <α>_D²⁵: (II), 73, -2.75 deg; (III), 80, 80.8 deg; (IV), 50, +37.25 deg; (V), 50, +0.8.The IR and PMR spectra of (II - IV), the 13C NMR spectra of (II) and (III), and the mass spectrum of (IV) are given.