Prepn from appropriate alkylmagnesium bromide and allyl bromide or chloride: Geisler, Pilz, Ber. 95, 96 (1962); from formaldehyde or paraformaldehyde and triphenyl(phenylmethylene)phosphorane: Hauser et al., J. Org. Chem. 28, 372 (1963); by catalytic dehydration of 2-octanol: Lundeen, Hoozer, J. Am. Chem. Soc. 85, 2180 (1963).