Synthesis of (R,S)‐muscone from 10‐undecenoic acid

Muscone (3‐methylcyclopentadecanone) is a major macrocyclic ketone found in the solid secretion, commonly known as musk, from the pouch of Moschus moschiferus . Herein, we report its synthesis from 10‐undecenoic acid, which is the major product of castor oil pyrolysis. Methyl 14‐oxotetradecanoate was prepared by radical addition of methyl 10‐undecenoate to acrolein. The terminal oxo group was protected as an acetal, and the ester group was treated with the anion of dimethyl methylphosphonate (CH 3 ‐(O)P(OMe) 2 , DMMP) to give 2‐(15‐dimethoxyphosphynil‐14‐oxo‐pentadecane)‐1,3‐dioxolane. The acetal protection was removed and the Emmons‐Horner reaction was carried out in K 2 CO 3 ‐ t ‐butanol to give 2‐cyclopenta‐decenone. The addition of MeMgI in the presence of Cu 2 Cl 2 gave muscone.