2023-09-132023-09-132014Xie, J.-B., Luo, J., Winn, T.R., Cordes, D.B., & Li, G.. 2014. Group-Assisted Purification (GAP) Chemistry for the Synthesis of Velcade via Asymmetric Borylation of N-Phosphinylimines. Beilstein Journal of Organic Chemistry, 10. https://doi.org/10.3762/bjoc.10.69https://doi.org/10.3762/bjoc.10.69https://hdl.handle.net/2346/96038cc-byA new approach to the anticancer drug Velcade was developed by performing asymmetric borylation of an imine anchored with a chiral N-phosphinyl auxiliary. Throughout the 7-step synthesis, especially in the imine's synthesis and in the asymmetric borylation reactions, operations and work-up were conducted in simple and easy ways without any column chromatographic purification, which defines the GAP (group-assisted purification) chemistry concept. It was found that the optically pure isomer (dr > 99:1) can be readily obtained by washing the crude mixture of the asymmetric borylation reaction with hexane; the chiral N-phosphinyl auxiliary can be easily recovered after deprotection is finished. Several other N-phosphinylimines were also investigated for the asymmetric borylation reaction. The absolute configuration of the borylation product was confirmed by single crystal X-ray diffraction analysis.© 2014 Xie et al.engAsymmetric borylationGAP chemistryN-phosphinylimineOrganophosphorousVelcadeArticle