Journal
ACS CATALYSIS
Volume 9, Issue 7, Pages 5881-5889Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acscatal.9b01579
Keywords
alkene; hydroallylation; carbodicarbene ligands; rhodium catalysis; allyltrifluoroborates
Categories
Funding
- NSF [CHE-1665125]
- University of North Carolina at Chapel Hill
- Burroughs-Welcome fellowship from the UNC Chemistry Department
- National Science Foundation [CHE1726291]
Ask authors/readers for more resources
Catalytic site-selective hydroallylation of vinyl arenes and 1,3-dienes is reported. Transformations are promoted by a readily accessible bidentate carbodicarbene-rhodium complex and involve commercially available allyltrifluoroborates and an alcohol. The reaction is applicable to vinyl arenes and aryl or alkyl-substituted 1,3-dienes (30 examples). Allyl addition products are generated in 40-78% yield and in up to >98:2 site selectivity. Reaction outcomes are consistent with the intermediacy of a Rh(III)-hydride generated by protonation of Rh(I) by an acid. A number of key mechanistic details of the reaction are presented: (1) Deuterium scrambling into the product and starting alkene indicates reversible Rh(III)-H migratory insertion. (2) A large primary kinetic isotope effect is observed. (3) With substituted allyltrifluoroborates (e.g., crotyl-BF3K) mixtures of site isomers are generated as a result of transmetalation followed by Rh-(allyl) complex equilibration, consequently disproving outer-sphere addition of the allyl nucleophile to Rh(III)-(eta(3)-allyl). (4) Stereochemical analysis of a cyclohexadiene allyl addition product supports a syn Rh(III)-hydride addition. (5) A Hammett plot shows a negative slope. Finally, utility is highlighted by a iodocyclization and cross metathesis.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available