A Novel Stereocontrolled Synthesis of Cyclopropyl-Substituted α,β-Unsaturated Esters: Palladium Catalyzed Cross-coupling of Cyclopropylboronic Acids with Bromoacrylates

A novel method of stereocontrolled preparing some cyclopropyl substituted α,β-unsaturated esters is described, based upon the palladium catalyzed cross-coupling reaction of bromoacrylates with trans-2-alkyl(aryl)cyclopropylboronic acids. It was found that using toluene as a solvent and in the presence of K₃PO₄ · 3 H₂O and catalytic amount of Pd(PPh₃)₄ the bromoacrylates could readily take part in the cross-coupling reaction with cyclopropylboronic acids at 100 °C, giving corresponding stereodefined cyclopropyl substituted α,β-unsaturated esters in good to excellent yields.

cyclopropylboronic acid - bromoacrylate - Suzuki reaction - palladium catalyzed cross-coupling - cyclopropyl-substituted α,β-unsaturated ester