Organocatalyzed Enantioselective [3+2] Cycloaddition Reactions for Synthesis of
Hong-Yan Liu1,2, Da-Ming Du1,2
1School of Chemistry and Chemical Engineering, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Beijing 100081, China.
Abstract:
An organocatalytic enantioselective [3+2] cycloaddition reaction involving 2-arylidene-1,3-indandiones and N-2,2-difluoroethylbenzothiophenone imines was developed. This approach efficiently afforded dispiro[benzothiophenone-indandione-pyrrolidine]s, featuring three stereocenters, in 84-98% yields with 3-93% ee and 9:1->20:1 dr. Notably, the method maintained its yield and enantioselectivity integrity even in a gram-scale amplification experiment. For example, the product with substituents on aromatics were obtained in 90% yield with 91% ee and >20:1 dr. Its absolute configuration was established through X-ray single-crystal diffraction analysis, and a plausible reaction mechanism was proposed.
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