Conjugate addition-enantioselective protonation to forge tertiary stereocentres α to azaarenes via cooperative hydrogen atom transfer and chiral hydrogen-bonding catalysis

• Published in: Chinese journal of catalysis Vol. 43; no. 3; pp. 558 - 563
• Main Authors: Tan, Yaqi, Yin, Yanli, Cao, Shanshan, Zhao, Xiaowei, Qu, Guirong, Jiang, Zhiyong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2022
• Subjects: Azaarenes; Cooperative catalysis; Enantioselective protonation; Hydrogen atom transfer; Photocatalysis; Cooperative catalysis; Azaarenes; Hydrogen atom transfer; Enantioselective protonation; Photocatalysis
• ISSN: 1872-2067; 1872-2067
• DOI: 10.1016/S1872-2067(21)63887-1

Cooperative hydrogen atom transfer and chiral hydrogen-bonding catalysis as a new platform for the asymmetric synthesis of azaarene derivatives is reported. By using a tetrabutylammonium decatungstate as the photocatalyst and a chiral phosphoric acid as the hydrogen-bonding catalyst, transformations of a variety of commercially available hydrocarbons and silanes with diverse α-branched 2-vinylazaarenes could efficiently experience a tandem radical conjugate addition and enantioselective protonation process, providing a convenient and fully atom economical approach to access a range of valuable enantioenriched α-tertiary azaarenes in high yields with good to excellent enantioselectivities (up to 93% ee). Through the direct use of tert-butyl methylcarbamate as the feedstock, this method enables a highly practical and concise synthesis of the enantiomerically pure medicinal molecule pheniramine (Avil). Cooperative hydrogen atom transfer and chiral hydrogen-bonding catalysis is explored to establish a new platform for accessing enantioenriched azaarene derivatives.