Organocatalytic Asymmetric [3 + 2] Cyclization: Enantioselective Synthesis of α-Indolyl Pyrrolo[1,2-a]indole
Hanxiao Shen1, Kanghua Rui1, Xufeng Lin1
1Department of Chemistry, Zhejiang University, Hangzhou 310058, China.
Abstract:
A novel asymmetric [3 + 2] cyclization of α-indolyl propargylic alcohols with 3-alkyl-1H-indoles via chiral phosphoric acid catalysis has been established. This strategy allowed the synthesis of chiral α-indolyl pyrrolo[1,2-a]indole derivatives with high yields (up to 91%) and excellent enantioselectivities (up to 99% ee), facilitating both the reaction activity and enantioselectivity by using the solvent of CH3CFCl2. Significantly, this protocol will provide an effective synthetic approach for constructing enantioenriched α-indolyl pyrrolo[1,2-a]indole cores of antimalarial natural product isoborreverine analogues.
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