Highly enantioselective construction of carbazole derivatives via [4+2] cycloaddition of silyloxyvinylindoles and β,γ-unsaturated α-ketoesters.

A highly efficient catalytic asymmetric [4+2] cycloaddition of silyloxyvinylindoles with β,γ-unsaturated α-ketoesters has been accomplished by an available chiral N,N′-dioxide/yttrium triflate complex. A widespread range of carbazole derivatives were obtained in 47–98% yield with 86–99% ee under mild reaction conditions. [ABSTRACT FROM AUTHOR]