Synthesis and reactivity of a terminal 1-alkynyl triazene Christeena Mathew, Kay Severin* Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland 1-Alkynyl triazenes have emerged as highly versatile reagents in organic synthesis. 1 The electron-donating character of the triazene group activates the triple bond, resulting in ynamide-like reactivity. 1-Alkynyl triazenes can be employed as suitable substrates for a variety of reactions, including cycloadditions, annulations, rearrangements, and 1,2-additions, as well as fluorination reactions. A distinct advantage of using 1-alkynyl triazenes in these transformations is the possibility for further derivatizations of the products. Under acidic conditions, the triazene function can be substituted by a variety of nucleophiles, facilitating divergent product modifications. 1 Thus far, 1-alkynyl triazenes have been accessible only by one synthetic route, namely, the coupling of lithium amides with first nitrous oxide (N 2 O) and then an alkynyl Grignard reagent. 2 The utilization of strongly basic and nucleophilic reagents severely restricts the functional groups, which can be employed. We have now developed a procedure for the synthesis of a terminal 1-alkynyl triazene. 3 The easy-to-access compound enables the preparation of 1-alkynyl triazenes with a range of functional groups including esters, alcohols, cyanides, phosphonates, and amides. The availability of functionalized 1-alkynyl triazenes makes this class of compounds attractive for applications in organic synthesis. The terminal 1-alkynyl triazene can also be used for the synthesis of di- and triynes and for the preparation of (hetero)aromatic triazenes via transition-metal-catalyzed cyclization reactions. 3
The authors greatly appreciate the financial support from EPFL as well as the facility/equipment available within EPFL. References 1. A. A. Suleymanov, K. Severin, Angew. Chem. Int. Ed. 2021 , 60 , 6879–6889. 2. G. Kiefer, T. Riedel, P. J. Dyson, R. Scopelliti, K. Severin, Angew. Chem., Int. Ed. 2015 , 54 , 302–305. 3. C. T. Bormann, C. Mathew, M. M. António, A. T. F. Fadaei-Tirani, K. Severin, J. Org. Chem. 2022 , 24 , 16882–16886.
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