Chiral oxazolidines acting as transient hydroxyalkyl-functionalized N-heterocyclic carbenes: an efficient route to air stable copper and gold complexes for asymmetric catalysis

Delphine Pichon-Barré, Ziyun Zhang, Aël Cador, Thomas Vives, Thierry Roisnel, Olivier Baslé, Lucie Jarrige, Luigi Cavallo, Laura Falivene, Marc Mauduit

Research output: Contribution to journalArticlepeer-review

Abstract

Optically pure oxazolidines were synthesized in nearly quantitative yields from chiral hydroxyalkyl-functionalized imidazolinium salts. Acting as transient chiral diamino N-heterocyclic carbenes (NHCs), these oxazolidines allowed the efficient formation of well-defined copper(I) and gold(I) hydroxyalkyl-NHC complexes, which could be isolated, for the first time, as air stable complexes after silica gel chromatography. Interestingly, X-ray analysis of gold complexes revealed that the hydroxyl-function is not chelated to the metal. Computational studies suggested that both cyclisation to produce oxazolidine and O–H bond elimination to form the transient carbene (prior to coordination) occur through a concerted mechanism. The novel chiral copper-catalysts, as well as oxazolidines alone (copper free), demonstrated excellent performances in asymmetric conjugate addition and allylic alkylation with high regio- and enantio-selectivities (up to 99% ee).
Original languageEnglish (US)
JournalChemical Science
DOIs
StatePublished - Jul 11 2022

ASJC Scopus subject areas

  • Chemistry(all)

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