Enantioselective Synthesis of 4-Substituted Dihydrocoumarins through a Zinc Bis(hydroxyamide)-Catalyzed Conjugate Addition of Terminal Alkynes

A new enantioselective catalyst for the conjugate addition of terminal alkynes has been developed. Terminal alkynes react with 3-alkoxycarbonylcoumarins in the presence of diethylzinc and bis(hydroxyamide) ligands to give chiral non-racemic dihydrocoumarins substituted with an alkynyl group on the C-4 position with good yields and enantiomeric excesses up to 95%.Financial support from the Ministerio de Economia y Competitividad (Gobierno de Espana) and FEDER (European Union) (CTQ2009-13083) and from Generalitat Valenciana (ACOMP2012-212 and ISIC2012/001) is gratefully acknowledged. A. S.-M. thanks the MEC for a pre-doctoral grant (FPI).Blay, G.; Muñoz Roca, MDC.; Pedro, JR.; Sanz-Marco, A. (2013). Enantioselective Synthesis of 4-Substituted Dihydrocoumarins through a Zinc Bis(hydroxyamide)-Catalyzed Conjugate Addition of Terminal Alkynes. Advanced Synthesis and Catalysis. 355:1071-1076. doi:10.1002/adsc.201201120S1071107635