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Diastereo‐ and Enantioselective Synthesis of Spiro‐Pyrrolidine‐Pyrazolones by Squaramide‐Catalyzed Cascade Aza‐Michael/Michael Reactions
Author(s) -
Li JunHua,
Wen Hongliang,
Liu Lei,
Du DaMing
Publication year - 2016
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201600316
Subject(s) - squaramide , pyrrolidine , chemistry , michael reaction , bifunctional , enantioselective synthesis , cascade reaction , diastereomer , pyrazolones , organocatalysis , catalysis , organic chemistry , stereochemistry
A new method was developed to rapidly generate a series of spiro‐pyrrolidine‐pyrazolones by using a squaramide‐catalyzed cascade aza‐Michael/Michael addition of either tosylaminomethyl enones or enoates to unsaturated pyrazolones. This tandem reaction sequence proceeded well by using 5 mol‐% of a chiral bifunctional tertiary amine squaramide catalyst to afford the desired products in good to excellent yields (up to 98 %) with excellent diastereoselectivities [up to >20:1 diastereomeric ratio ( dr )] and high to excellent enantioselectivities (up to 98 % ee ).