Facile modular synthesis of jasmonoyl--isoleucine analogs possessing a pyrazolidin-3-one core

A short and flexible route to pyrazolidin-3-one analogs of the phytohormone (+)-7-iso-jasmonoyl- l -isoleucine is presented. The compounds were assembled from four basic building blocks, namely a pyrazolidin-3-one core, alkyl chain, linker and amino ester or acid. The efficacy of this approach was demonstrated in the synthesis of 11 analogs with variations in all parts of the molecule. Several pyrazolidine-3-one analogs of (+)-7-iso-jasmonoyl- l -isoleucine, the main phytohormone involved in plant responses to biotic or abiotic stress, were prepared from 4 different building blocks in just a few steps.