Enantioselective Synthesis of Quaternary Carbon Stereocenters: Addition of 3-Substituted Oxindoles to Vinyl Sulfone Catalyzed by Pentanidiums

Lili Zong; Shubo Du; Kek Foo Chin; Chao Wang; Choon-Hong Tan

doi:10.1002/anie.201503844

Enantioselective Synthesis of Quaternary Carbon Stereocenters: Addition of 3-Substituted Oxindoles to Vinyl Sulfone Catalyzed by Pentanidiums

Angew Chem Int Ed Engl. 2015 Aug 3;54(32):9390-3. doi: 10.1002/anie.201503844. Epub 2015 Jul 15.

Authors

Lili Zong¹, Shubo Du¹, Kek Foo Chin¹, Chao Wang¹, Choon-Hong Tan²

Affiliations

¹ Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore).
² Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore). choonhong@ntu.edu.sg.

PMID: 26179829
DOI: 10.1002/anie.201503844

Abstract

A pentanidium-catalyzed highly enantioselective conjugate addition of 3-alkyloxindoles to phenyl vinyl sulfone has been demonstrated. This approach allows the construction of 3,3-dialkyl-substituted oxindole frameworks with high yield and excellent enantioselectivity (up to 99%) under simple phase-transfer conditions. A variety of oxindoles bearing all-carbon quaternary stereogenic centers were obtained in the presence of 0.25 mol% pentanidium. Meanwhile, practicality was illustrated by a gram-scale asymmetric synthesis of two 3,3-dialkyl-substituted oxindoles. The resulting adduct can be smoothly transformed to the natural product analogue in a short synthetic route.

Keywords: conjugate addition; organocatalysis; pentanidium; quaternary carbon stereocenter; sulfones.