A new convergent synthesis of (±)‐methyl jasmonate based on a C4 + C6 synthon approach

A new, convergent synthesis of (±)‐methyl jasmonate is presented. The strategy is based on a C4+C6 synthon approach. The C4 fragment N,4,4‐trimethoxy‐N‐methyl‐butanamide ( 5 ) was prepared in 4 steps starting from chloroacetyl chloride via the previously unreported N,4,4‐trimethoxy‐N‐methylbut‐2‐enamide ( 4 ). The coupling of 5 with the C6 synthon, cis ‐3‐hexenyl magnesium chloride ( 6 ), provided easy access to ( Z )‐4‐oxodec‐7‐enal ( 8 ). The latter was converted to the key intermediate ( Z )‐2‐(pent‐2‐en‐1‐yl)cyclopent‐2‐en‐1‐one ( 9 ) from which (±)‐methyl jasmonate can be obtained in high yield using well‐established procedures.