A new convergent synthesis of (±)-methyl jasmonate based on a C4ￂ +ￂ 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.