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CuI-Catalyzed Coupling Reactions of 4-Iodopyrazoles and Alcohols: Application toward Withasomnine and Homologs |
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| Authors: | Yoshihide Usami Yumika Kubo Toshiki Takagaki Nao Kuroiwa Jun Ono Kohei Nishikawa Ayaka Nakamizu Yuya Tatsui Shinya Harusawa Noboru Hayama Hiroki Yoneyama |
| Institution: | Department of Pharmaceutical Organic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan; (Y.K.); (T.T.); (N.K.); (J.O.); (K.N.); (A.N.); (Y.T.); (S.H.); (N.H.); (H.Y.) |
| 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. |
| Keywords: | synthesis 4-alkoxypyrazole CuI coupling reaction microwave withasomnine homologue |