Catalytic asymmetric benzylic C-H activation by means of carbenoid-induced C-H insertions.
Tetrakis[N-[4-dodecylphenyl)sulfonyl]-(S)-prolinate]dirhodium [Rh(2)(S-DOSP)(4)]-catalyzed decomposition of methyl aryldiazoacetates in the presence of substituted ethylbenzenes results in benzylic C-H activation by means of a rhodium-carbenoid-induced C-H insertion. A Hammet study showed that positive charge buildup occurred on the benzylic carbon in the transition state of the C-H activation step. C-H activation of toluene and isopropylbenzene is possible, but a competing double cyclopropanation occurs with these substrates. The C-H activation is highly regioselective and enantioselective, and in certain cases, moderate diastereoselectivity is also possible.
Davies
Huw M L
HM
Department of Chemistry, University at Buffalo, State University of New York, 14260-3000, USA. hdavies@acsu.buffalo.edu
Jin
Qihui
Q
Ren
Pingda
P
Kovalevsky
Andrey Yu
AY