Catalytic Asymmetric Cycloaddition of In Situ-Generated ortho-Quinone Methides and Azlactones by a Triple Brønsted Acid Activation Strategy

• Published in: Chemistry : a European journal Vol. 22; no. 20; pp. 6774 - 6778
• Main Authors: Yu, Xiao-Ye, Chen, Jia-Rong, Wei, Qiang, Cheng, Hong-Gang, Liu, Zhi-Cheng, Xiao, Wen-Jing
• Format: Journal Article
• Language: English
• Published: WEINHEIM Blackwell Publishing Ltd 10.05.2016; Wiley; Wiley Subscription Services, Inc
• Subjects: Activation; Asymmetry; Bearing; Catalysis; Chemistry; Chemistry, Multidisciplinary; Cycloaddition; Enantiomers; heterocycles; lactones; methides; Physical Sciences; Quinones; Science & Technology; Strategy; synthetic methods; SULFUR YLIDES; ENANTIOSELECTIVE SYNTHESIS; TRIARYLMETHANES; methides; FORMAL 4+1 ANNULATION; CLASSIFICATION; lactones; cycloaddition; heterocycles; DIELS-ALDER REACTION; CONSTRUCTION; DERIVATIVES; synthetic methods; IN-SITU; DIHYDROCOUMARINS
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.201601227

A convergent and highly stereoselective [4+2] cycloaddition of in situ‐generated ortho‐Quinone methides (o‐QMs) and azlactone enols has been successfully developed through a triple Brønsted acid catalysis strategy. This protocol provides an efficient and mild access to various densely functionalized dihydrocoumarins bearing adjacent quaternary and tertiary stereogenic centers in high yields with excellent diastereo‐ and enantioselectivity. Triple activation! A convergent and highly stereoselective [4+2] cycloaddition of in situ generated ortho‐Quinone methides (o‐QMs) and azlactone enols has been successfully developed through a triple Brønsted acid catalysis strategy. This protocol provides an efficient and mild access to various densely functionalized dihydrocoumarins (see scheme).