Year: 2024
Type: article
Abstract: The homogeneous catalytic hydrogenation of benzo-fused heteroarenes generally provides partially hydrogenated products wherein the heteroaryl ring is preferentially reduced, such as quinoline hydrogenation, leading to 1,2,3,4-tetrahydroquinoline. Herein, we report a carbocycle-selective hydrogenation of fused N -heteroarenes (quinoline, isoquinoline, quinoxaline, etc.) using the Ru complex of a chiral spiroketal-based diphosphine (SKP) as the catalyst, affording the corresponding 5,6,7,8-tetrahydro products in high chemoselectivities. This catalytic system is also effective for the asymmetric carbocycle hydrogenation of fused heteroarenes bearing a boryl or amino group. Experimental studies provided a strong support for the homogeneous nature of the catalysis, and an inner-sphere mechanism was proposed for the hydrogenation. DFT calculations indicated that the hydrogenation is initiated by η 4 -coordinative activation of quinoline carbocycle to Ru dihydride complex of SKP, followed by metal-to-ligand hydride transfer. Subsequent carbocycle reduction proceeds via consecutive steps of the H 2 oxidative addition and C–H reductive elimination.
DOI: 10.1021/jacs.4c05365
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W4405274980