Methods for preparing self-aldol condensation products of prenyl aldehyde (3-methyl-2-butenal) by use of an amine catalyst under weakly acidic conditions at temperatures of 10° C. or higher are disclosed. Methods are disclosed for the selective formation of α-1,2-adducts and γ-1,2-adducts of prenyl aldehyde, and for the formation of specialty compositions useful in the flavor and fragrance industries.