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

In the presence of Pd(PPh3)(4), NaBr and KF . 2H(2)O the cross-coupling rea ction of heteroaryl triflates with trans-cyclopropylboronic acids proceeds readily to give pure trans-cyclopropyl heteroarenes in moderate to good yie lds. The X-ray crystallography of compound 3g and H-1-NMR spectra of all pr oducts show that the configuration of the cyclopropyl group was retained du ring the reaction. Under the same reaction conditions, highly optically act ive cyclopropyl-substituted heteroarenes (up to 94% ee) were obtained by cr oss-coupling of heteroary/triflates with enantiomerically enriched cyclopro pylboronic acids.