Borane Catalyzed Selective Diazo Cross‐Coupling Towards Pyrazoles. Issue 4 (8th December 2021)

• Record Type: Journal Article
• Authors: Dasgupta, Ayan; Pahar, Sanjukta; Babaahmadi, Rasool; Gierlichs, Lukas; Yates, Brian F.; Ariafard, Alireza; Melen, Rebecca L.
• Is Part Of: Advanced synthesis & catalysis. Volume 364:Issue 4(2022)
• Page Start: 773
• Page End: 780
• Publication Date: 2021-12-08
• Subjects: Diazoester -- Pyrazole -- Carbene -- Tris(pentafluorophenyl)borane -- Density Functional Theory; Catalysis -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Chemistry -- Periodicals; Chemistry, Technical -- Periodicals; Chemistry -- Periodicals; Catalysis -- Periodicals; Technology, Pharmaceutical -- Periodicals; 547.2
• DOI: 10.1002/adsc.202101312
• Languages: English
• ISSNs: 1615-4150

Abstract

Abstract: Decomposition of donor‐acceptor diazo compounds leads to the formation of reactive carbene intermediates. These can undergo a wide variety of carbene transfer reactions to yield synthetically useful products. Herein, we report a selective borane catalyzed cyclization reaction from the combination of two different diazo compounds to afford N‐substituted pyrazoles. The selective decomposition of the more reactive α‐aryl α‐diazoester and subsequent reaction with a vinyl diazoacetate produces N‐alkylated pyrazoles in a regioselective manner. Catalytic amounts of tris(pentafluorophenyl)borane (10 mol%) were employed to afford the pyrazole products (36 examples) in yields from 59 to 80%. Extensive DFT studies have been undertaken to interpret the mechanism for this reaction which was found to go through two tandem catalytic cycles, both catalyzed by B(C6 F5 )3 . Abstract :