Efficient
axially chiral cyclic phosphoric acid catalyzed enantioselective sequential
additions of 2-aryl-3H-indol-3-ones, aldehydes, and
diethyl 2-aminomalonate have been developed, and a new type of nitrogen-containing
heterocyclic compounds, 2,3-dihydro-1H-imidazo[1,5-a]indol-9(9aH)-one derivatives, were prepared
in good yields and excellent ee values with a wide functional group
tolerance, in which the reactivity and enantioselectivity of the substrates
were enabled by our newly developed axially chiral cyclic phosphoric
acid, (R)-CYC-9-CPA. Furthermore, the corresponding
1H-imidazo[1,5-a]indol-9(9aH)-ones were constructed through the easy oxidation of 2,3-dihydro-1H-imidazo[1,5-a]indol-9(9aH)-one derivatives.