Selective Synthesis of Chiral Carbocycles by Iridium-Catalyzed Asymmetric Mono‑, Double‑, or Triple Hydrogenation of Cyclic Dienones

TL;DR

A new iridium-catalyzed method allows the selective synthesis of chiral carbocycles from cyclic dienones with high efficiency and stereopurity.

Contribution

The development of a single-step asymmetric hydrogenation protocol to produce multiple stereopure carbocycles from a single precursor.

Findings

The π-bonds in cyclic dienones are hydrogenated sequentially, favoring specific conformations.

Up to three stereocenters can be installed in one step with high yield and stereopurity.

The method provides a multistep synthesis alternative for accessing stereopure carbocycles.

Abstract

A divergent N,P-iridium-catalyzed
asymmetric hydrogenation of cyclic
dienones into chiral cyclohexenones, cyclohexanones, or cyclohexanols
is described. The π-bonds in cyclic dienones underwent hydrogenation
in a sequential manner, favoring the (s)-cis conformed
alkene followed by the olefin in the (s)-trans conformation
and at last the ketone, to install up to three stereocenters in a
single step. The simple choice of the proper catalyst allowed the
formation of each respective product in high yield and stereopurity
(up to 99% ee, up to 99/1 d.r.). This protocol provides
an interesting opportunity to access multiple and stereopure carbocycles
starting from the same precursor that otherwise require multistep
syntheses.

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