Diastereo‐ and Enantioselective Synthesis of Spiro‐Pyrrolidine‐Pyr­azolones by Squaramide‐Catalyzed Cascade Aza‐Michael/Michael Reactions. Issue 14 (24th April 2016)

• Record Type: Journal Article
• Authors: Li, Jun‐Hua; Wen, Hongliang; Liu, Lei; Du, Da‐Ming
• Is Part Of: European journal of organic chemistry. Issue 14(2016)
• Page Start: 2492
• Page End: 2499
• Publication Date: 2016-04-24
• Subjects: Asymmetric synthesis -- Organocatalysis -- Domino reactions -- Michael addition -- Spiro compounds -- Nitrogen heterocycles; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201600316
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: 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 ). Abstract : A squaramide‐catalyzed cascade aza‐Michael/Michael addition of either tosylaminomethyl enones or enoates to unsaturated pyrazolones was developed. This new method affords spiro‐pyrrolidine‐pyrazolones 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 ).