Triflyl azide production

To complete the synthesis of the diazofluorene, the cyclization product 126 is treated with diisopropylethylamine and triflyl azide [50], to afford the diazofluorene 127 in 81 % yield. Under these conditions, the hydroxyfulvene is likely deprotonated to generate a cyclopentadienyl anion. Attack of this anion on the trifyl azide reagent... 

A versatile stereoselective synthesis of endo,exo-furofuranones was accomplished by R.C.D. Brown and coworkers. One of the key steps was a Rh(ll)-catalyzed C-H insertion reaction and the required diazo lactone was prepared via the Regitz diazo transfer reaction. The 2-acetyl substituted lactone substrate proved to be recalcitrant toward the deacylative diazo transfer under standard conditions. Eventually the authors decided to use the very reactive triflyl azide (TfNs), which was generated in situ under phase-transfer conditions to afford the desired a-diazo lactone. The C-H insertion product was then converted to (+)-methylxanthoxylol. 

The natural product (-)-oxetanocin is an unprecedented oxetanosyl-A/-glycoside that inhibits the in vitro replication of human immunodeficiency virus (HIV). In order to prepare multigram quantities of the compound, D.W. Norbeck et al. devised a short and efficient synthetic strategy. The cornerstone of the strategy was the Wolff rearrangement of a five-membered diazo ketone. The diazo transfer was achieved by first converting the ketone to an enamino ketone followed by treatment with triflyl azide. Upon irradiation with a 450 W Pyrex filtered Hanovia lamp, the isomeric oxetanes (a 3 = 2 1) were obtained in 36% yield. 

Another advantage of sterically demanding trisyl azide is the selective azidation of cyclic 8-ketoesters (eq 32). Thus, the desired azidation product A was slowly formed as a single product in either THF or MeCN. In contrast, more reactive sulfonyl azides such as 4-methoxybenzenesulfonyl azide, 4-nitrobenzenesulfonyl azide, mesyl azide, triflyl azide, and tosyl azide provided not only the azidation product A but also a ring-contraction product B, a ring-opened diazo-transfer product C, and a mixture of ring-opened olefins D. The amounts of by-products B, C, and D were dependent upon the azide reagent. 

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