Diastereodivergent organocatalysis for the asymmetric synthesis of chiral annulated furans
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Authors: | Charlie Verrier Paolo Melchiorre |
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Affiliation: | a ICREA – Catalan Institution for Research and Advanced Studies , Pg. Lluís Companys 23 , 08010 Barcelona , Spain . Email: ; Tel: +34 977920208 ;b ICIQ – Institute of Chemical Research of Catalonia , Av. Països Catalans 16 , 43007 Tarragona , Spain |
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Abstract: | Disclosed herein is a stereoselective method for the synthesis of 2,3-furan fused carbocycles bearing adjacent quaternary and tertiary carbon stereocenters. The chemistry is based on an asymmetric addition of β-ketoesters to 2-(1-alkynyl)-2-alkene-1-ones catalysed by natural cinchona alkaloids followed by a silver-catalysed intramolecular cycloisomerisation. By exploiting the distinct catalysis modes of quinine, which can act either as a general base or, upon opportune modifications, as a phase transfer catalyst, a complete switch of the enforced sense of diastereoinduction is achieved. The stereodivergent systems enable access to the full matrix of all possible stereoisomeric products. |
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