Usami Y, Kubo Y, Takagaki T, Kuroiwa N, Ono J, Nishikawa K, Nakamizu A, Tatsui Y, Harusawa S, Hayama N, Yoneyama H. CuI-Catalyzed Coupling Reactions of 4-Iodopyrazoles and Alcohols: Application toward
Withasomnine and Homologs.
Molecules 2021;
26:3370. [PMID:
34199652 PMCID:
PMC8199780 DOI:
10.3390/molecules26113370]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/25/2021] [Accepted: 05/31/2021] [Indexed: 12/03/2022] Open
Abstract
The direct 4-alkoxylation of 4-iodo-1H-pyrazoles with alcohols was achieved by a CuI-catalyzed coupling protocol. The optimal reaction conditions employed excess alcohol and potassium t-butoxide (2 equiv) in the presence of CuI (20 mol%) and 3,4,7,8-tetramethyl-1,10-phenanthroline (20 mol%) at 130 °C for 1 h under microwave irradiation. The present method was efficiently applied to the synthesis of withasomnine and its six- and seven-membered cyclic homologs.
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