Copper-Catalyzed [3+3] Cycloaddition of Ethynyl Methylene Cyclic Carbamates with N,N'-Cyclic Azomethine Imines
Ya-Hui Li1,2, Xiang-Ping Hu1
1Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
Abstract:
A copper-catalyzed diastereoselective cross [3+3] dipolar cycloaddition of ethynyl methylene cyclic carbamates with N,N'-cyclic azomethine imines has been realized. The presence of an extended C═C bond in N,N'-cyclic azomethine imines distinctively changes the reaction pathway, enabling the precise regioselective control of ethynyl methylene cyclic carbamates serving as C1,C3-dipoles rather than sterically favorable C1,N-ones, thus delivering a range of N-(7-ethynyl-3-oxo-7-phenyl-8-((E)-styryl)-2,3,7,8-tetrahydro-1H-pyrazolo[1,2-a]pyridazin-6-yl)benzenesulfonamides in up to 93% yields.
Related Concept Videos
Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Cycloaddition Reactions: Overview
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Cycloaddition Reactions: MO Requirements for Thermal Activation
Cycloaddition Reactions: MO Requirements for Photochemical Activation


![[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)