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With toluene-4-sulfonic acid; In toluene; at 130℃; for 4h;
To a solution of a compound 1 (262 mg, 2.0 mmol) in toluene (5 mL) were added a compound II (368 mg, 2.0 mmol) and p-toluenesulfonic acid monohydrate (19 mg, 0.1 mmol), and the resulting solution was stirred at 130 °C for 4 hours. The reaction mixture was poured into saturated sodium bicarbonate aqueous solution and extracted with ethyl acetate, then the organic layer was washed with saturated brine. The organic layer was dried over anhydrous magnesium sulfate, concentrated in vacuo to give a compound III (281 mg, Yield 47percent) as yellow oil. The obtained compound III was used for the next reaction without further purification. 1 H NMR (DMSO-d6) delta: 0.78-0.84 (m, 4H), 1.24-1.28 (m, 3H), 1.40 (s, 9H), 1.90-2.00 (m, 1H), 4.10-4.25 (m ,4.H), 5.78 (d, J = 1.2 Hz, 1H), 10.01 (brs, 1H).
tert-butyl 2-(3-(trimethylsilyl)propiolamido)acetate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
64%
Isobutyl chloroformate (357.2 mg, 2.6 mmol) was dropwise added to a solution of <strong>[5683-31-8]3-(trimethylsilyl)propiolic acid</strong> 25 (372 mg, 2.6 mmol) and NMM (344 mg, 3.4 mmol) in THF (10 mL) at -40 oC. The reaction was stirred at -40 to -10 oC for 40 min. A solution of tert-butyl 2-aminoacetate 26 (447 mg, 3.4 mmol) and NMM (344 mg, 3.4 mmol) in co-solvents THF/DMF (5 mL/1 mL) was slowly added to the reaction solution at -40 oC for 20 min. The mixture slowly recovered to r.t. from -40oC and was stirred overnight at r.t.. After concentration, the residue was dissolved in CH2Cl2, washed by NaHCO3 and brine, dried by Na2SO4 and purified by silica gel column chromatography (5-10% EtOAc/Hexanes, stepwise gradient by 5%, then 10% iPrOH /Hexanes) to afford 27. Yield: 428 mg, 64%. 1H NMR (CDCl3, 600 MHz) 6.41 (b, 1H), 3.97 (d, J = 5.4 Hz, 1H), 1.49 (s, 9H), 0.23 (s, 9H). MS (ESI) [M+H]+ 256.4, found 256.0.
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