Insights into the in Vitro and in Vivo SAR of Abscisic Acid – Exploring Unprecedented Variations of the Side Chain via Cross‐Coupling‐Mediated Syntheses

Abstract

Novel analogues of the plant hormone abscisic acid (ABA) were designed and prepared to explore the impact that modifications of its terpenoid side chain have on receptor affinity and in vivo efficacy against drought stress in selected crops. Their efficient and versatile synthesis proceeded via Stille or Sonogashira couplings, shortening the synthetic route significantly. In line with molecular modelling and X‐ray crystallography studies novel ABA‐derivatives with small alkyl, cycloalkyl or haloalkyl substituents showed strong effects in vitro and in vivo against drought stress in crops, particularly canola and wheat.