Desilylation-Activated Propargylic Transformation: Enantioselective Copper-Catalyzed [3+2] Cycloaddition of Propargylic Esters with β-Naphthol or Phenol Derivatives

• Published in: Angewandte Chemie International Edition Vol. 55; no. 16; pp. 5014 - 5018
• Main Authors: Shao, Long, Wang, Ya-Hui, Zhang, De-Yang, Xu, Jie, Hu, Xiang-Ping
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 11.04.2016
• Subjects: asymmetric catalysis; copper; cycloaddition; heterocycles; reaction mechanisms; reaction mechanisms; copper; cycloaddition; asymmetric catalysis; heterocycles
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201510793

A copper‐catalyzed asymmetric [3+2] cycloaddition of 3‐trimethylsilylpropargylic esters with either β‐naphthols or electron‐rich phenols has been realized and proceeds by a desilylation‐activated process. Under the catalysis of Cu(OAc)2⋅H2O in combination with a structurally optimized ketimine P,N,N‐ligand, a wide range of optically active 1,2‐dihydronaphtho[2,1‐b]furans or 2,3‐dihydrobenzofurans were obtained in good yields and with high enantioselectivities (up to 96 % ee). This represents the first desilylation‐activated catalytic asymmetric propargylic transformation. Cu on active duty: The highly enantioselective title reaction of 3‐trimethylsilylpropargylic acetates has been realized on the basis of a desilylation‐activated strategy. With the support of a finely modified ketimine P,N,N‐ligand, the reaction gave rise to either chiral 1,2‐dihydronaphtho‐ or benzofurans in good yields and with up to 96 % ee.