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Iridium-Catalyzed Asymmetric Hydrogenation of 4,6-Disubstituted 2‑Hydroxypyrimidines

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journal contribution
posted on 01.10.2018, 11:34 by Guang-Shou Feng, Lei Shi, Fan-Jie Meng, Mu-Wang Chen, Yong-Gui Zhou
An efficient iridium-catalyzed hydrogenation of 4,6-disubstituted 2-hydroxypyrimidines has been achieved, giving chiral cyclic ureas with excellent diastereoselectivities and up to 96% ee of enantioselectivities. In the presence of the in situ generated hydrogen halide, the equilibrium of the lactame–lactime tautomerism of 2-hydroxypyrimidine is more toward the oxo form with lower aromaticity, which effectively improves the reactivity to facilitate hydrogenation. Moreover, the cyclic ureas could be readily converted into chiral 1,3-diamine derivatives without loss of optical purity.