Catalytic Enantioselective and Regioselective [3+3] Cycloadditions Using 2-Indolylmethanols as 3 C Building Blocks

Abstract

The first catalytic asymmetric cycloaddition using 2-indolylmethanols as 3C building blocks has been established by a chiral phosphoric acid-catalyzed enantioselective and regioselective [3+3] cycloaddition of 2-indolylmethanols with azomethine ylides, which constructed biologically important tetrahydro-γ-carboline frameworks in high yields and excellent enantioselectivities (up to 83 % yield, 99:1 e.r.). This reaction not only represents the first application of 2-indolylmethanols as 3C building blocks in catalytic asymmetric cycloadditions, but also has established an abnormal regioselectivity in indolylmethanol-involved transformations.

Keywords: asymmetric catalysis; azomethine ylide; cycloaddition; enantioselectivity; organocatalysis.