Light-driven deracemization enabled by excited-state electron transfer

Nick Y. Shin, Jonathan M. Ryss, Xin Zhang, Scott J. Miller, Robert R. Knowles

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Deracemization is an attractive strategy for asymmetric synthesis, but intrinsic energetic challenges have limited its development. Here, we report a deracemization method in which amine derivatives undergo spontaneous optical enrichment upon exposure to visible light in the presence of three distinct molecular catalysts. Initiated by an excited-state iridium chromophore, this reaction proceeds through a sequence of favorable electron, proton, and hydrogen-atom transfer steps that serve to break and reform a stereogenic C–H bond. The enantioselectivity in these reactions is jointly determined by two independent stereoselective steps that occur in sequence within the catalytic cycle, giving rise to a composite selectivity that is higher than that of either step individually. These reactions represent a distinct approach to creating out-of-equilibrium product distributions between substrate enantiomers using excited-state redox events.

Original languageEnglish (US)
Pages (from-to)364-369
Number of pages6
JournalScience
Volume366
Issue number6463
DOIs
StatePublished - Oct 18 2019

All Science Journal Classification (ASJC) codes

  • General

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