Process for making a conjugated diene from an allyl alcohol

A method for the in-situ formation of a conjugated diene of formula (III) from an allyl alcohol of formula (I), the method comprising converting the allyl alcohol of formula (I)

• to an allyl carbonate, allyl ester, or allyl formate of formula (II)
• in the presence of a base followed by converting the allyl carbonate, allyl ester, or allyl formate of formula (II) to the conjugated diene of formula (III)
• using a palladium catalyst or palladium catalyst precursor and an organic phosphorous ligand,
• wherein
• each R1 is independently selected from H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, aromatic hydrocarbon, and substituted aromatic hydrocarbon;
• R2 is selected from H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, aromatic hydrocarbon, and substituted aromatic hydrocarbon;
• R3 is selected from H, alkyl, substituted alkyl, alkoxy, substituted alkoxy, phenyl, and substituted phenyl;
• each R4 is independently selected from H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, aromatic hydrocarbon, and substituted aromatic hydrocarbon;
• and
• wherein at least one R1 bears a proton in a-position of the allylic C3 group which is deprotonated under basic reaction conditions thus forming a diene of formula (III) via 1,2 or 1,4 elimination and the at least one R1 is alkyl, substituted alkyl, alkenyl, substituted alkenyl, aromatic hydrocarbon, or substituted aromatic hydrocarbon.