A reaction of N-sulfonyl-1,2,3-triazole with boron trifluoride etherate afforded a (Z)-β-ensulfonylamido fluoride instead of the previously erroneously assigned E isomer. The correction of the stereochemistry was based on a ge-1D ROESY NMR experiment and X-ray crystal structure analyses. Application of the reaction to N-fluoroalkyl-1,2,3-triazoles afforded new (Z)-β-enamido fluorides in a stereoselective manner. A mechanism involving coordination of BF3 with the triazole ring and vinyl diazonium and vinyl cation intermediates was proposed.

N‐Alkenyl compounds are versatile synthetic building blocks and their stereoselective transformations are key processes in the synthesis of many prominent classes of natural products, pharmaceuticals, and agrochemicals. However, a large structural variety of known N‐alkenyl compounds and their diverse reactivity have so far precluded the development of a general method for their stereoselective synthesis. Herein we present an aluminum halide‐mediated, highly stereoselective, efficient and scalable transformation of commercially available N‐fluoroalkyl‐1,2,3‐triazoles to N‐haloalkenyl imidoyl halides, and demonstrate their use in the synthesis of stereodefined N‐alkenyl amides, amidines, imines, hydrazonoamides, imidothioates, iminophosphonates, 1,2,4‐triazoles and tetrazoles. The reaction is of wide scope on both the triazole substrate and aluminum halide, providing highly functionalized products. Mechanistic and computational investigations suggest a reaction mechanism involving the triazole ring opening, initiated by the coordination of nitrogen one of the triazole ring to the Lewis acid, N2 elimination and the formation of a vinyl cation intermediate, which reacts with nitrogen‐bound aluminum halide, followed by a series of halide exchange reactions on C−X and Al−X bonds.

4-Aryl-5-allyl-N-fluoroalkyl-1,2,3-triazoles available by a three-component reaction of fluoroalkyl azides, copper acetylides, and allyl halides underwent aluminum halide-mediated transformation to N-(4-halo-2-aryl-cyclopentenyl) imidoyl halides by cyclization of vinyl cation intermediates, followed by halide capture. Utilization of the cyclic products was demonstrated by the synthesis of N-alkenyl amides, amidines, isoquinolines, and tetrazoles or by the subsequent modification of the cyclopentene ring.

The front cover picture illustrates the reaction of N‐fluoroalkylated‐1,2,3‐triazoles with aluminum trihalide, proceeding via a vinyl cation (illustrated as the structure in brackets in the middle) to afford structurally diverse N‐haloalkenyl imidoyl halides. These products are formed in a stereoselective fashion on both double bonds and have been utilized in the synthesis of various N‐alkenyl compounds, such as enamides, enamidines, enimines, N‐alkenyl tetrazoles, and other. In this work, Beier and co‐workers show a new, mild and efficient 1,2,3‐triazole denitrogenative ring‐opening process mediated by easily available Lewis acids. Details can be found in the Full Paper by Beier and co‐workers (A. Markos, L. Janecký, T. Chvojka, T. Martinek, H. Martinez‐Seara, B. Klepetářová, P. Beier, Adv. Synth. Catal. 2021, 363, 3258–3266; DOI: 10.1002/adsc.202100009).