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Medium and Large N-Heterocycle Formation via Allene Hydroamination with a Bimetallic Rh(I) Catalyst
- Publication Year :
- 2021
- Publisher :
- Cambridge University Press (CUP), 2021.
-
Abstract
- We report the synthesis of a bimetallic Rh(I) complex containing a bridging CO ligand that facilitates Rh–Rh bond formation. This bimetallic complex enables intramolecular allene hydroamination to form seven to ten-member rings in high yield. Monometallic Rh complexes, in contrast, fail to achieve any product formation. We demonstrate a broad substrate scope for formation of a variety of N-heterocycles in good to excellent yields. Macrocyclization reactions that form eleven to fifteen-membered heterocycles are also demonstrated. Mechanistic studies show that the reaction likely proceeds via catalyst protonation by trifluoroacetic acid, followed by reversible allene insertion and C–N bond-forming reductive elimination. The difference in product selectivity observed with our bimetallic catalyst vs monometallic Rh complexes may result from cooperativity between the two metals.
Details
- Database :
- OpenAIRE
- Accession number :
- edsair.doi...........af3da884e07c3b4c83781bda84f08f1c