THE SYNTHESIS OF D(6)-ALPHA-FARNESENE

d(6)-alpha-Famesene (3,7-dimethyl-11-H-2(3)-methyl-12,12,12-H-2(3)-dodeca-1,3E,6E,10-tetraene) has been synthesised by two routes. Thermolysis of 2-geranyl-3-methylsulpholene (5) yielded unlabelled alpha-famesene (93%) which was epoxidized at Delta 10 in 31% yield. Oxidative cleavage of the epoxide (42%) and Wittig elaboration of the resultant trienal with d(6)-Isopropyl triphenylphosphorane gave d(6)-alpha-famesene (73%). Alternatively, selective epoxidation of (5) gave the terminal 6',7' mono-epoxide in 74% yield. Oxidative cleavage (73%) and Wittig elaboration of the resultant aldehyde;yielded deuterated 2-geranyl-3-methylsulpholene (46%). Thermal elimination of sulphur dioxide afforded the title compound in 91% yield.