Birch Reaction Followed by Asymmetric Ir-Catalyzed Hydrogenation

Significance

The preparation of 1,3- or 1,4-di­substituted cyclohexanes remains a challenging task, especially in the case of 1,3-trans or 1,4-cis isomers. In this work, the Birch reduction products were subjected to iridium-mediated asymmetric hydrogenation to give trans-1,3-disubstituted cyclohexanes with enantioselectivities up to >99% ee. The catalysts could be deactivated using poly(4-vinylpyridine) to produce only monohydrogenated adducts. The partial catalyst poisoning could also be achieved using AcOK, whereas most other additives eliminated the reactivity completely.