NOVELTY - Synthesizing substituted 2-allyl-benzaldehyde compounds (I) comprises: hydrolyzing substituted lithium (2-allylphenyl)(amino)methanolate compounds (II); or (a) contacting substituted benzaldehyde compounds (IV) with substituted amines (V) or (VI) or substituted alcohols (VII) in presence of organolithium, (b) contacting product from step (a) with organolithium to form ortho-lithiated product, and contacting the ortho-lithiated product with copper cyanide to form a cuprate, (c) contacting the cuprate from the step (b) with an allyl halide, and (d) hydrolyzing the product of the step (c).    USE - The method is useful in synthesizing (I) (claimed) which is used as an intermediate in the synthesis of prostacylin analogs e.g. treprostinil.    ADVANTAGE - The method: reduces the overall number of synthetic steps; saves time; avoids the use of extra chemicals, manpower and large volume of solvents; permits the synthesis to be carried out at ambient temperature without the need for cryogenic equipment; eliminates tedious column chromatographic purifications; and provides the desired product with improved yield and chemical purity.    DETAILED DESCRIPTION - Synthesizing substituted 2-allyl-benzaldehyde compounds of formula (I) comprises: hydrolyzing substituted lithium (2-allylphenyl)(amino)methanolate compounds of formula (II); or (a) contacting substituted benzaldehyde compounds of formula (IV) with substituted amines of formula (R1-NH2) (V) or (R1R2N-(CHR3)x-NHR1) (VI) or substituted alcohols of formula (R3-OH) (VII) in the presence of an organolithium, (b) contacting the product from the step (a) with an organolithium to form an ortho-lithiated product, and contacting the ortho-lithiated product with copper cyanide to form a cuprate, (c) contacting the cuprate from the step (b) with an allyl halide comprising allyl chloride, allyl bromide or allyl iodide, and (d) hydrolyzing the product of the step (c) to give (I).    R = alcohol protecting group, H, 1-6C alkyl, 6-14C aryl or 6-14C aryl(1-6C alkylene);    R1, R2, R3 = H, 1-6C alkyl, 3-6C cycloalkyl, 3-14C aryl, 3-14C aryl(1-6C alkylene) or 3-6C cycloalkyl(1-6C alkylene); and    x = 0-4.