Copper Catalyzed 3+2 Annulation Reaction of Exocyclic Sulfonyl Enamides for the Synthesis of N,O-Spiroketal and Spiroketal

• Published in: Chemistry : a European journal Vol. 30; no. 44; p. e202401062
• Main Authors: Cheng, Wen-Fu, Gao, Shan-Zeng, Yang, Yu-Chen, Wang, Lijia
• Format: Journal Article
• Language: English
• Published: 06.08.2024
• ISSN: 1521-3765; 1521-3765
• DOI: 10.1002/chem.202401062

A copper-catalyzed [3+2] annulation reaction of exocyclic enamines/enol ethers with 1,4-benzoquinone esters has been developed, providing facile access to N,O-spiroketals and spiroketals under mild conditions with broad substrate scope (26 examples, 71-94 % yields). Gram scale synthesis and chemical transformations demonstrated that this method is potentially useful in the synthesis of natural products and drugs containing a N,O- spiroketal moiety. The chiral N,O-spiroketal could be obtained with 98 % ee after recrystallization, when a chiral SaBOX ligand was employed.A copper-catalyzed [3+2] annulation reaction of exocyclic enamines/enol ethers with 1,4-benzoquinone esters has been developed, providing facile access to N,O-spiroketals and spiroketals under mild conditions with broad substrate scope (26 examples, 71-94 % yields). Gram scale synthesis and chemical transformations demonstrated that this method is potentially useful in the synthesis of natural products and drugs containing a N,O- spiroketal moiety. The chiral N,O-spiroketal could be obtained with 98 % ee after recrystallization, when a chiral SaBOX ligand was employed.