Teaming up: The title reaction has been developed to deliver the product α‐alkylidene‐γ‐butyrolactones as single diastereomers with up to 98 % ee (see scheme; Ts=4‐toluenesulfonyl). The enantioselective process is catalyzed by 1, which contains both Lewis base and Brønsted acid moieties.

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Teambildung: Die Titelreaktion bietet diastereoselektiven Zugang zu α‐Alkyliden‐γ‐butyrolactonen mit bis zu 98 % ee (siehe Schema; Ts=4‐Toluolsulfonyl). Der enantioselektive Prozess wird durch den Organokatalysator 1 katalysiert, der sowohl Lewis‐basische als auch Brønsted‐saure Einheiten enthält.

Facile Synthesis of α-Methylidene-γ-butyrolactones: Intramolecular Rauhut--Currier Reaction Promoted by Chiral Acid-Base Organocatalysts. -Highly functionalized α-methylidene-γ-butyrolactones are formed enantioselectively from prochiral dienone enolates in the presence of chiral organocatalysts (CHOC). The reaction fails if either the dienone α-positions or the side chain terminal olefin are substituted. -(TAKIZAWA, S.; NGUYEN, T. M.-N.; GROSSMANN, A.; SUZUKI, M.; ENDERS, D.; SASAI*, H.; Tetrahedron 69 (2013) 3, 1202-1209, http://dx.