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129896-49-7

tert-butyl 3-ethynyl-1H-indole-1-carboxylate synthesis

5synthesis methods
-

Yield:129896-49-7 95%

Reaction Conditions:

Stage #1: tert-butyl 3-iodo-1H-indole-1-carboxylate;trimethylsilylacetylenewith [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium(II);copper (I) iodide;triethylamine in tetrahydrofuran at 20; for 12 h;Reflux;Inert atmosphere;Sonogashira Cross-Coupling;
Stage #2: with N,N,N-tributylbutan-1-aminium fluoride in tetrahydrofuran at 20; for 0.5 h;Inert atmosphere;Sonogashira Cross-Coupling;

Steps:

A.II General method E - Sonogashira coupling - TMS-deprotection (1)

General procedure: In an oven-dried round bottom flask equipped with a reflux condenser and under argon atmosphere, the corresponding 3-iodo-l /-indole (1.00 equiv.), bis(triphenylphosphine)palladium(II) dichloride (2 mol%) and copper(I) iodide (4 mol%) were combined in dry tetrahydrofuran (C ~ 0.2 M). The reaction mixture was degassed with argon over 5 minutes before a slowly addition of trimethylsilylacetylene (1.50 equiv.) and dry triethylamine (2.00 equiv.). The reaction was stirred at room temperature for 12 hours (monitored by TLC), then 1M solution of tetrabutylammonium fluoride in tetrahydrofuran (1.50 equiv.) was added dropwise through a syringe and the mixture was stirred at room temperature for 0.5 hours until the complete deprotection (monitored by TLC). The resulting solution was quenched by addition of a saturated solution aqueous of ammonium chloride and extracted with ethyl acetate three times. The combined organic extracts were washed with brine, dried (MgSCri) and filtered. The solvents were removed in vacuo and the residue was purified by column chromatography on silica gel to yield the desired product.

References:

WO2022/8475,2022,A1 Location in patent:Page/Page column 71; 80; 88; 146-147