Carbazole‐Based N‐Heterocyclic Carbenes for the Promotion of Copper‐Catalyzed Palladium‐Free Homo‐/Hetero‐Coupling of Alkynes and Sonogashira Reactions. Issue 2 (27th January 2020)

• Record Type: Journal Article
• Authors: Ramsingh Girase, Tejpalsingh; Bhilare, Shatrughn; Sankar Murthy Bandaru, Siva; Chrysochos, Nicolas; Schulzke, Carola; Sanghvi, Yogesh S.; Kapdi, Anant R.
• Is Part Of: Asian journal of organic chemistry. Volume 9:Issue 2(2020)
• Page Start: 274
• Page End: 291
• Publication Date: 2020-01-27
• Subjects: carbazoles -- N-heterocyclic carbenes -- palladium -- Sonogashira reaction -- heterocoupling -- homocoupling; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; 547.005
• DOI: 10.1002/ajoc.202000016
• Languages: English
• ISSNs: 2193-5807

Abstract

Abstract: Alkynes are useful synthetic building blocks that occur in many naturally occurring molecules and have the potential to be easily modified for further natural products and drug synthesis applications. Given the‐versatility of the alkyne functionality, ‐various synthetic methods (mostly palladium‐based) are known in the literature, allowing the installation to take place under different reaction conditions. A single catalytic system (without Pd) however, if developed could provide a single point solution for the installation of the alkyne moiety and keeping this in mind, we report herein a highly active palladium‐free Cu/carbazole‐based NHC catalyst system allowing homocoupling and heterocoupling of alkynes at ambient temperature. Using a combination of Cu/NHC‐catalyzed homocoupling/deprotection/heterocoupling sequence tetraynes have also been synthesized in good yields. The Cu/NHC catalyst system was also able to catalyze a palladium‐free Sonogashira reaction of synthetically useful nucleosides. Abstract : Triple bonds everywhere : Alkynes are useful synthetic building blocks that occur in many naturally occurring molecules and have the potential to be easily modified for further natural products and drug synthesis applications. Given the‐versatility of the alkyne functionality, ‐various synthetic methods (most palladium‐based) are known in literature allowing the installation to take place under different reaction conditions. A single catalytic system (without Pd) however, if developed could provide a single point solution for the installation of the alkyne moiety and keeping this in mind, we report herein a highly active palladium‐free Cu/carbazole‐based NHC catalyst system allowing homocoupling and heterocoupling of alkynes at ambient temperature. Using a combination of Cu/NHC‐catalyzed homocoupling/deprotection/heterocoupling sequence tetraynes have also been synthesized in good yields. The Cu/NHC catalyst system was also able to catalyze a palladium‐free Sonogashira reaction of synthetically useful nucleosides.