Superacidic activation of 1- and 3-isoquinolinols and their electrophilic reactions.
Isomeric 1- and 3-isoquinolinols (11 and 12) when activated in CF(3)SO(3)H-SbF(5) acid system undergo selective ionic hydrogenation with cyclohexane to give 5,6,7,8-tetrahydro-1(2H)- and 5,6,7,8-tetrahydro-3(2H)-isoquinolinones (22 and 27). Under the influence of aluminum chloride similar products were also obtained along with 3,4-dihydro-1(2H)- and 1,4-dihydro-3(2H)-isoquinolinones (23 and 28), respectively. Compounds 11 and 12 also condense with benzene in the presence of aluminum halides, under mild conditions, to give 3,4-dihydro-3-phenyl-1(2H)- and 1,4-dihydro-1-phenyl-3(2H)-isoquinolinones (24 and 29), respectively. Prolonged reaction time or catalysis under strongly acidic HBr-AlBr(3) provides an alternative reaction pathway to yield 5,6-dihydro-6,8-diphenyl-1(2H)- and 5,6,7,8-tetrahydro-6,8-diphenyl-3(2H)-isoquinolinones (25 and 30), respectively. Products 24 and 29 were also found to revert back to 11 and 12 in the presence of aluminum halides in o-dichlorobenzene. The mechanism of these intriguing reactions, which involves superelectrophilic dicationic intermediates, is discussed.
Koltunov
Konstantin Yu
KY
Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles 90089-1661, USA.
Prakash
G K Surya
GK
Rasul
Golam
G
Olah
George A
GA