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Computational and Experimental Insights into Asymmetric Rh‐Catalyzed Hydrocarboxylation with CO 2
Author(s) -
Pavlovic Ljiljana,
Pettersen Martin,
Gevorgyan Ashot,
Vaitla Janakiram,
Bayer Annette,
Hopmann Kathrin H.
Publication year - 2021
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.202001469
Subject(s) - chemistry , oxazoline , denticity , imidazole , enantioselective synthesis , nucleophile , catalysis , transition state , ligand (biochemistry) , enantiomer , medicinal chemistry , stereochemistry , stacking , combinatorial chemistry , computational chemistry , organic chemistry , biochemistry , receptor , crystal structure
The asymmetric Rh‐catalyzed hydrocarboxylation of α,β‐unsaturated carbonyl compounds was originally developed by Mikami and co‐workers but gives only moderate enantiomeric excesses. In order to understand the factors controlling the enantioselectivity and to propose novel ligands for this reaction, we have used computational and experimental methods to study the Rh‐catalyzed hydrocarboxylation with different bidentate ligands. The analysis of the C−CO 2 bond formation transition states with DFT methods shows a preference for outer‐sphere CO 2 insertion, where CO 2 can undergo a backside or frontside reaction with the nucleophile. The two ligands that prefer a frontside reaction, StackPhos and t Bu‐BOX, display an intriguing stacking interaction between CO 2 and an N‐heterocyclic ring of the ligand (imidazole or oxazoline). Our experimental results support the computationally predicted low enantiomeric excesses and highlight the difficulty in developing a highly selective version of this reaction.