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  • Highly efficient and stereocontrolled construction of 3,3'-pyrrolidonyl spirooxindoles via organocatalytic domino Michael/cyclization reaction.

Highly efficient and stereocontrolled construction of 3,3'-pyrrolidonyl spirooxindoles via organocatalytic domino Michael/cyclization reaction.

Organic letters (2013-03-05)
Xiong-Li Liu, Wen-Yong Han, Xiao-Mei Zhang, Wei-Cheng Yuan
ABSTRACT

A wide range of structurally diverse 3,3'-thiopyrrolidonyl spirooxindoles bearing three contiguous stereogenic centers can be smoothly obtained via a domino Michael/cyclization reaction between 3-isothiocyanato oxindoles and 3-methyl-4-nitro-5-alkenyl-isoxazoles with commercially available quinine as the catalyst under mild conditions. The protocol is significantly characterized by high reactivity, a low catalyst loading (1 mol %), and an excellent diastereo- and enantioselectivity (up to >99:1 dr and 98% ee).

MATERIALS
Product Number
Brand
Product Description

Supelco
Quinine, certified reference material, TraceCERT®, Manufactured by: Sigma-Aldrich Production GmbH, Switzerland
Sigma-Aldrich
Quinine, suitable for fluorescence, anhydrous, ≥98.0% (dried material, NT)
Sigma-Aldrich
Quinine, 90%