A practical approach to stereodefined cyclopropyl-substituted heteroarenes using a Suzuki-type reaction

Abstract

In the presence of Pd(PPh₃)₄, NaBr and KF·2H₂O the cross-coupling reaction of heteroaryl triflates with trans-cyclopropylboronic acids proceeds readily to give pure trans-cyclopropyl heteroarenes in moderate to good yields. The X-ray crystallography of compound 3g and ¹H-NMR spectra of all products show that the configuration of the cyclopropyl group was retained during the reaction. Under the same reaction conditions, highly optically active cyclopropyl-substituted heteroarenes (up to 94% ee) were obtained by cross-coupling of heteroary/triflates with enantiomerically enriched cyclopropylboronic acids.