[EN] PROCESSES FOR PRODUCING OPTICALLY PURE ß-LACTONES FROM ALDEHYDES AND COMPOSITIONS PRODUCED THEREBY [FR] PROCÉDÉS DE FABRICATION DE BÊTA-LACTONES OPTIQUEMENT PURES À PARTIR D'ALDÉHYDES ET COMPOSITIONS OBTENUES PAR CES PROCÉDÉS
Reaction Rate Acceleration
Enabled by Tethered Lewis Acid-Lewis Base Bifunctional
Catalysis: A Catalytic, Enantioselective [2+2] Ketene
Aldehyde Cycloaddition Reaction
作者:Yun-Ming Lin、Sridhar Chidara
DOI:10.1055/s-0029-1217332
日期:——
asymmetric [2+2] cycloaddition reaction between ketene and aldehydes rapidly. The LA * ―LB * bifunctional catalyst, a quinine tethered Co(III)―salen complex (5 mol%) catalyzes the [2+2] cycloaddition reaction to produce the C4-substituted β-lactone in uniformly >99% ee and high isolated yields (71―97%). The dramatic rate acceleration, the hallmark of cooperative intramolecular bifunctional catalysis, is achieved