Enantioselective Oxidative (4+3) Cycloadditions between Allenamides and Furans through Bifunctional Hydrogen‐Bonding/Ion‐Pairing Interactions. Issue 35 (26th July 2017)

• Record Type: Journal Article
• Authors: Villar, Laura; Uria, Uxue; Martínez, Jose I.; Prieto, Liher; Reyes, Efraim; Carrillo, Luisa; Vicario, Jose L.
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 35(2017)
• Page Start: 10535
• Page End: 10538
• Publication Date: 2017-07-26
• Subjects: asymmetric catalysis -- cycloaddition -- ion-pairing catalysis -- organocatalysis -- oxygen heterocycles; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201704804
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: BINOL‐based N‐trifluoromethanesulfonyl phosphoramides catalyze the enantioselective (4+3) cycloaddition between furans and oxyallyl cations, the latter being generated in situ by oxidation of allenamides. The chiral organic phosphoramide counteranion is proposed to engage in the activation of the oxyallyl cation intermediate through cooperative hydrogen‐bonding and ion‐pairing interactions, enabling an efficient chirality transfer that provide the final adducts with high diastereo‐ and enantioselectivities. Remarkably, the reaction shows a wide substrate scope that includes a variety of substituted allenamides and furans. Abstract : Opposite charges attract : In situ generated oxyallyl cations react with a variety of furans in the presence of a BINOL‐based N ‐sulfonyl phosphoramide catalyst, furnishing (4+3) cycloaddition products in excellent yields and with high stereocontrol. The reaction is enabled by bifunctional activation of the oxyallyl cation by hydrogen bonding in combination with the formation of a tightly bound ion pair.