Synthesis of an M + 7 stable isotope of γ-cyhalothrin

γ‐Cyhalothrin is a single isomer, synthetic pyrethroid insecticide. This material was originally developed and marketed by Pytech Chemicals, a joint venture between Dow AgroSciences and Cheminova A/S. Cheminova A/S now wholly owns Pytech Chemical. As a part of registration studies, there was a need for a stable isotope of γ‐cyhalothrin to serve as an internal standard. This paper will discuss the 11‐step synthesis that was used to prepare an M + 7 stable isotope of γ‐cyhalothrin by utilizing triethyl phosphonoacetate‐d2 and acetone‐d6 to incorporate deuterium into the molecule. In the end, the diastereomers were separated by preparative reverse‐phase HPLC to give γ‐cyhalothrin‐d7 in an overall yield of 6%. Copyright © 2012 John Wiley & Sons, Ltd. An 11‐step synthetic route for preparing γ‐cyhalothrin‐d7 from relatively inexpensive triethyl phosphonoacetate‐d2 and acetone‐d6 is described.