Easy access to isoquinolines and tetrahydroquinolines from ketoximes and alkynes via rhodium-catalyzed C-H bond activation.
Described herein is a convenient and highly regioselective synthesis of substituted isoquinoline derivatives from various aromatic ketoximes and alkynes via a one-pot, rhodium-catalyzed C-H bond activation. In addition, tetrahydroquinoline derivatives are formed in good yields from 2-arylidene-1-cyclohexanone oximes possessing an exocyclic double bond and from tetrahydroxanthone oximes. A possible mechanism is proposed that involves chelation-assisted C-H activation via oxidative addition of Rh(I) to an ortho-C-H bond, insertion of the alkyne, reductive elimination, intramolecular electrocyclization, and aromatization. This mechanism is supported by isolation of the ortho-alkenylation products 7p and 7q. Also described herein is an example of an iridium-catalyzed activation of an sp(3) C-H bond.
Parthasarathy
Kanniyappan
K
Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan.
Cheng
Chien-Hong
CH
D000480:Alkynes / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D006859:Hydrogen / Q000737:chemistry*; D006912:Hydroxyquinolines / Q000138:chemical synthesis* / Q000737:chemistry; D007546:Isoquinolines / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D010091:Oximes / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
D000480:Alkynes; D006912:Hydroxyquinolines; D007546:Isoquinolines; D010091:Oximes; D002244:Carbon; D006859:Hydrogen; D012238:Rhodium