Gold-catalysed asymmetric net addition of unactivated propargylic C-H bonds to tethered aldehydes.

Nat Catal

Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA.

Published: February 2021

The asymmetric one-step net addition of unactivated propargylic C-H bond to aldehyde leads to an atom-economic construction of versatile chiral propargylic alcohols but has not been realized previously. Here we show its implementation in an intramolecular manner under mild reaction conditions. Via cooperative gold catalysis enabled by a chiral bifunctional phosphine ligand, this chemistry achieves asymmetric catalytic deprotonation of propargylic C-H (pK > 30) by a tertiary amine group (pK ~ 10) of the ligand in the presence of much more acidic aldehydic α-hydrogens (pKa ~ 17). The reaction exhibits a broad scope and readily accommodates various functional groups. The 5-/6-membered ring fused homopropargylic alcohol products are formed with excellent enantiomeric excesses and high selectivities with or without a preexisting substrate chiral center. DFT studies of the reaction support the conceived reaction mechanism and the calculated energetics corroborate the observed stereoselectivity and confirm an additional metal-ligand cooperation.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8574197PMC
http://dx.doi.org/10.1038/s41929-020-00569-8DOI Listing

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