Triflyl azide diazo transfer reaction

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. 

Scheme 3.24 Alkyl azides via the diazo transfer reaction using triflyl...

A. Titz, Z. Radic, O. Schwardt and B. Ernst, A safe and convenient method for the preparation of triflyl azide, and its use in diazo transfer reactions to... 

---