methyl (2S)-2-isocyanatopropanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of 250 mg of methyl 4-[2-(4-{[(2-{[3-({[2-(methylamino)ethyl](pentan-3-yl)amino}methyl)benzoyl]amino}-4,5,6,7-tetrahydro-1-benzothiophen-3-yl)carbonyl]amino}phenyl)ethyl]benzoate, 0.20 mL of N-ethyl-N-isopropylpropan-2-amine and 10 mL of THF under ice cooling was added 70 mg of methyl(S)-(−)-2-isocyanatopropionate, followed by stirring for 1 hour at the same temperature and then for 2 hours at room temperature. Ethyl acetate and an aqueous sodium hydrogen carbonate solution were added to the reaction mixture, followed by extraction with ethyl acetate. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. The residue was purified by silica gel column chromatography (10% methanol/chloroform), thereby obtaining 290 mg methyl 4-{2-[4-({[2-({3-[(4S)-4,7-dimethyl-3,6-dioxo-10-(pentan-3-yl)-2-oxa-5,7,10-triazaundecan-11-yl]benzoyl}amino)-4,5,6,7-tetrahydro-1-benzothiophen-3-yl]carbonyl}amino)phenyl]ethyl}benzoate. for 2 hours at room temperature followed by extraction with ethyl acetate The organic layer was washed with saturated brine dried over anhydrous sodium sulfate the solvent was removed under reduced pressure The residue was purified by silica gel column chromatography (10% methanol/chloroform)