Efficient and Stereospecific Synthesis of (z)-Hex-3-Enedioic Acid, a Key Intermediate for Gly-Gly cis Olefin Isostere

Abstract (z)-Hex-3-enedioic acid, a key intermediate in the synthesis of (z)-5-amino-3-pentenoic acid (a Gly-Gly cis olefin isostere), was synthesized by a short and efficient procedure of sequential oxidations. Thus, selective mono epoxidation of 1,4-cyclohexadiene was followed by periodate oxidation to the appropriate dialdehyde. Finally, Jones oxidation of the dialdehyde afforded the corresponding diacid product.