A flow strategy for the rapid, safe and scalable synthesis of N-H 1, 2, 3-triazoles via acetic acid mediated cycloaddition between nitroalkene and NaN3. Issue 27 (6th July 2017)

• Record Type: Journal Article
• Authors: Li, Dong; Liu, Lei; Tian, Yu; Ai, Yongjian; Tang, Zhike; Sun, Hong-bin; Zhang, Gang
• Is Part Of: Tetrahedron. Volume 73:Issue 27/28(2017)
• Page Start: 3959
• Page End: 3965
• Publication Date: 2017-07-06
• Subjects: Continuous flow microreactor -- 1, 2, 3-Triazole -- Nitroalkene -- Acid promote -- In-tube retention time gradient; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2017.05.065
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: The N-unsubstituted 4-aryl-1H-1, 2, 3-triazoles were synthesized via the acetic acid promoted cycloaddition between β-nitrostyrenes with sodium azide under transition-metal-free conditions in a continuous flow microreactor. The continuous-flow microreactor provided a safe environment for the dangerous reagents NaN3 and nitroalkene, and offered such a rapid procedure that the triazoles were formed in less than 4 min. In addition, the excess sodium azide was quenched by the by-product HNO2 in the presence of acetic acid. The scale-up experiment proved again that the yield did not drop in the flow reaction. Moreover, the synthesis of N-unsubstituted 1, 2, 3-triazole was also explored via a one pot reaction with aldehyde, nitromethane and sodium azide, and this reaction was monitored with an "in-tube retention time gradient" (IT-RTG) technology, which may be a novel application of the continuous-flow microreactor. Graphical abstract: