A catalytic asymmetric conjugate allylation was successfully developed to synthesize potential pharmacologically active 4-allyl-2-oxochroman skeletons. A dual activation strategy was employed by using N,N′-dioxide-Yb(OTf)3 to activate coumarins and using (CuOTf)2•C7H8 to activate tetraallyltin viatransmetalation, respectively. Good yields and enantioselectivities were obtained under mild conditions
催化不对称共轭烯丙基化已成功开发,以合成潜在的药理活性的4-烯丙基-2-氧代苯并二氢吡喃骨架。通过使用N,N'-二氧化物-Yb(OTf)3激活香豆素并使用(CuOTf)2 •C 7 H 8来通过跨金属化激活四烯丙基环丁胺,采用双重激活策略。在温和的条件下获得了良好的收率和对映选择性。
Enantioselective Synthesis of 4-Substituted Dihydrocoumarins through a Zinc Bis(hydroxyamide)-Catalyzed Conjugate Addition of Terminal Alkynes
作者:Gonzalo Blay、M. Carmen Muñoz、José R. Pedro、Amparo Sanz-Marco
DOI:10.1002/adsc.201201120
日期:2013.4.15
A new enantioselective catalyst for the conjugateaddition of terminalalkynes has been developed. Terminalalkynes 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%.