Rhodium-Stabilized Diarylcarbenes Behaving as Donor/Acceptor Carbenes

• Type of Material: Article
• Authors: Maizie Lee, Emory University; Zhi Ren, Emory University; Djamaladdin Musaev, Emory University; Huw Davies, Emory University
• Language: English
• Date: 2020-06-05
• Publisher: AMER CHEMICAL SOC
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2020 American Chemical Society
• Final Published Version (URL): http://dx.doi.org/10.1021/acscatal.0c01131
• Title of Journal or Parent Work: ACS CATALYSIS
• Volume: 10
• Issue: 11
• Start Page: 6240
• End Page: 6247
• Grant/Funding Information: HMLD is a named inventor on a patent entitled, Dirhodium Catalyst Compositions and Synthetic Processes Related Thereto (US 8,974,428, issued March 10, 2015). The other authors have no competing financial interests.
• Keywords: ENANTIOSELECTIVE SYNTHESIS; donor/acceptor carbene; CATALYSTS; ALKENES; CARBOXYLATES; Chemistry, Physical; enantioselective cyclopropanation; C-H INSERTION; CYCLOPROPANATION; diaryldiazomethane; donor/donor carbene; ORGANIC-SYNTHESIS; SELECTIVITY; Science & Technology; Physical Sciences; chiral dirhodium catalyst; ENHANCEMENT; ASYMMETRIC-SYNTHESIS; Chemistry

Abstract

Rhodium-stabilized diarylcarbenes typically generated from diaryldiazomethanes have been generally classified as donor/donor carbenes. This combined computational and experimental study demonstrates that diarylcarbenes display reactivity characteristics that are more reminiscent of donor/acceptor carbenes. When the reactions are carried out with the chiral dirhodium catalysts Rh2(S-PTAD)4 and Rh2(S-NTTL)4, highly enantioselective and diastereoselective cyclopropanations can be achieved, forming 1,1,2-triarylcyclopropanes. The reason for this behavior is because the two rings are unable to align in the plane of the rhodium carbene at the same time. The aryl ring aligned in the plane of the carbene behaves as a donor group, whereas the aryl ring aligned orthogonally behaves as an acceptor group.