Trityl chloride → tert-butyl (5S)-5-([3-(tert-butoxycarbonylamino)propionyl]amino}-6-([1-methyl-5-(tritylamino)-1H-pyrazol-4-yl]amino}-6-oxohexylcarbamate

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Reaction Steps

To a solution of the crude product of tert-butyl (5S)-6-[(5-amino-1-methyl-1H-pyrazol-4-yl)amino]-5-{[3-(tert-butoxycarbonylamino)propionyl]amino}-6-oxohexylcarbamate and triethylamine (0.50 g) in chloroform (30 ml) was added triphenylmethyl chloride (1.37 g), and the mixture was stirred at room temperature for 16 hours. The reaction mixture was washed successively with 10% aqueous citric acid solution, brine and saturated aqueous sodium hydrogencarbonate solution. The organic layer was dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography on silica gel eluting with 3% methanol/chloroform to give tert-butyl (5S)-5-{[3-(tert-butoxycarbonylamino)propionyl]amino}-6-{[1-methyl-5-(tritylamino)-1H-pyrazol-4-yl]amino}-6-oxohexylcarbamate (1.62 g) as an oil.

Provenance & Evidence