Fig. 3: Skeletal ring-expansion of indoles and pyrroles with functionalized N-triftosylhydrazones.
From: Halogencarbene-free Ciamician-Dennstedt single-atom skeletal editing
a Functionalized carbon-atom insertion of indoles. Reaction conditions: N-triftosylhydrazone (0.3 mmol), N-TBS indole (0.6 mmol), NaH (0.6 mmol) and TpBr3Ag(thf) (10 mol%) in PhCF3 (10 mL) at 60 °C under N2 for 12 h then TBAF (0.75 mmol) at 25 °C under air for 10 min. b One-carbon insertion of pyrroles. Reaction conditions: N-triftosylhydrazone (0.3 mmol), 1H-pyrrole (0.6 mmol), NaH (0.6 mmol) and Rh2(esp)2 (1 mol%) in PhCF3 (5 mL) at 60 °C under N2 for 12 h. Isolated yields. Rh2(esp)2, Bis[rhodium(α,α,α′,α′-tetramethyl-1,3-benzenedipropionic acid). a80 °C. bCsF/DMSO instead of TBAF. cThe OH group in indole or N-triftosylhydrazone was protected by TBS and deprotected in the reaction conditions. dDCM instead of PhCF3. eCsF/DMF instead of TBAF. f1 mol% Rh2(esp)2. gN-triftosylhydrazone derived from 3-(triisopropylsilyl)propiolaldehyde.
