A new approach to the utilization of highly reactive and unstable ortho-quinone methides (o-QMs) in catalytic asymmetric settings is presented. The enantioselective reactions are catalysed by bifunctional organocatalysts, and the o-QM intermediates are formed in situ from 2-sulfonylalkyl phenols through base-promoted elimination of sulfinic acid. The use of mild Brønsted basic conditions for transiently generating o-QMs in catalytic asymmetric processes is unprecedented, and allows engaging productively in the reactions nucleophiles such as Meldrum’s acid, malononitrile and 1,3-dicarbonyls. The catalytic transformations give new and general entries to 3,4-dihydrocoumarins, 4H-chromenes and xanthenones. These frameworks are recurring structures in natural product and medicinal chemistry, as testified by the formal syntheses of (R)-tolterodine and (S)-4-methoxydalbergione from the catalytic adducts.
Catalytic Asymmetric Addition of Meldrum's Acid, Malononitrile, and 1,3-Dicarbonyls to ortho-Quinone Methides Generated In Situ under Basic Conditions / Lorenzo, Caruana; Martina, Mondatori; Vasco, Corti; Sara, Morales; Andrea, Mazzanti; Mariafrancesca, Fochi; Luca, Bernardi. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - STAMPA. - 21:16(2015), pp. 6037-6041. [10.1002/chem.201500710]
Catalytic Asymmetric Addition of Meldrum's Acid, Malononitrile, and 1,3-Dicarbonyls to ortho-Quinone Methides Generated In Situ under Basic Conditions
CARUANA, LORENZO;CORTI, VASCO;MAZZANTI, ANDREA;FOCHI, MARIAFRANCESCA;BERNARDI, LUCA
2015
Abstract
A new approach to the utilization of highly reactive and unstable ortho-quinone methides (o-QMs) in catalytic asymmetric settings is presented. The enantioselective reactions are catalysed by bifunctional organocatalysts, and the o-QM intermediates are formed in situ from 2-sulfonylalkyl phenols through base-promoted elimination of sulfinic acid. The use of mild Brønsted basic conditions for transiently generating o-QMs in catalytic asymmetric processes is unprecedented, and allows engaging productively in the reactions nucleophiles such as Meldrum’s acid, malononitrile and 1,3-dicarbonyls. The catalytic transformations give new and general entries to 3,4-dihydrocoumarins, 4H-chromenes and xanthenones. These frameworks are recurring structures in natural product and medicinal chemistry, as testified by the formal syntheses of (R)-tolterodine and (S)-4-methoxydalbergione from the catalytic adducts.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.