Thirteen variously substituted α-ethylenic β'-allenic alcohols (1,5,6-triene-3-ols) have been synthesized by three different methods, for two of which the key step was the reaction of an organo copper reagent with a derivative of a β-hydroxy γ-ethylenic alcohol (1-ene-5-yne-3,7-diol). The[3,3]-sigmatropic rearrangement of these alcohols, following the heating of their solution in diglyme, leads to γ-dienic aldehydes and ketones. The yields are best (60–70%) for tertiary alcohols substituted on carbon 5. Comparisons of the reactivities of these 13 alcohols show that the mechanism of this rearrangement can probably vary, following the substitution from a cyclohexadiyl biradical process to a concerted pathway involving a cyclohexane transition state.