FLP‐Catalyzed Transfer Hydrogenation of Silyl Enol Ethers

Abstract

Herein we report the first catalytic transfer hydrogenation of silyl enol ethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6‐tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ‐terpinene as a dihydrogen surrogate. A variety of silyl enol ethers undergo efficient hydrogenation, with the reduced products isolated in excellent yields (29 examples, 82 % average yield).

Visible-Light-Mediated Amination of π-Nucleophiles with N-Aminopyridinium Salts

“…13 1-(Benzofuran-2-yl)-2-(Me,Ts-amino)ethanone (3l). Following the general procedure D, compound 3l was obtained from ((1-(benzofuran-2-yl)vinyl)oxy)(tert-butyl)dimethylsilane (0.25 mmol, prepared according to literature procedure 33 ) and N-aminopyridinium salt 1b (0.3 mmol). The crude product was purified by column chromatography to afford 67 mg of compound 3l as a white solid (yield = 78%, 16 h).…”

Photoredox-Catalyzed Generation of Sulfamyl Radicals: Sulfonamidation of Enol Silyl Ether with Chlorosulfonamide

“…The ion source is electrospray ionization (ESI). 1 H, 19 F NMR spectra were recorded at 400 MHz, and 13 C NMR spectra was recorded on 600 MHz. Chemical shifts in 1 H NMR spectra are reported in parts per million (ppm) on the δ scale from an internal standard of DMSO-d 6 (δ 2.50 ppm).…”

“…General Procedure for Preparation of Silyl Enol Ethers (GP-1). 19 A round-bottom flask containing a mixture of ketone (1.0 equiv, 10 mmol), sodium iodide (1.2 equiv, 12 mmol), and dry CH 3 CN (15 mL) was evacuated and filled with nitrogen three times, stirring for 5 min at room temperature. To the resulting solution, triethylamine (1.5 equiv, 15 mmol) and chlorotrimethylsilane (1.2 equiv, 12 mmol) were added.…”