Jenny Yang
Jenny Yang awarded a 2018 Sloan Research Fellowship.
Ryan McCarty awarded UC Presidential Postdoctoral Fellowship

Grad Zhiwei Chen from Dong Lab finds a way to make benzylic stereocenters

Chem Research
Sun, Nov 5

The selective semireduction of allenes is a synthetic challenge. Most existing conditions favour reduction of the terminal double bond to generate an achiral alkene. Methods to selectively reduce the corresponding internal double bond are scarce, and no enantioselective processes have been reported. In this communication, we show a regio- and enantioselective semireduction of allenes by Rh-hydride catalysis. A designed Josiphos ligand enables Rh-catalysis to generate chiral benzylic motifs, using a Hantzsch ester as the reductant. The semireduction proceeds chemoselectively in the presence of other functional groups, which are typically reduced using conventional hydrogenations. Isotopic labelling studies support a mechanism where the hydride is delivered to the branched position of a Rh-allyl intermediate.

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