Bis-cinchona alkaloid substituted pyrimidine ligands were found to give improved enantioselectivity in the osmium-catalyzed asymmetric dihydroxylation (AD) of monosubstituted terminal olefins.
Crispino, G. A., Jeong, K-S., Kolb, H. C., Wang, Z. M., Xu, D., & Sharpless, K. B. (1993). Improved enantioselectivity in asymmetric dihydroxylations of terminal olefins using pyrimidine ligands. Journal of Organic Chemistry, 58(3785), 3785-3786. https://doi.org/10.1021/jo00067a002