Formic Acid → O-({(3S)-4-[(6-{[(2R)-1-Amino-1-oxo-3-(tritylsulfanyl)propan-2-yl]amino}-6-oxohexyl)amino]-3-[(tert-butoxycarbonyl)amino]-4-oxobutyl}carbamoyl)-N-(tert-butoxycarbonyl)-L-tyrosine

Participants

Reaction Steps

250 mg (0.24 mmol) of the compound from example 22A was dissolved in approx. 5 ml tetrahydrofuran. 170 μl (1.22 mmol) Triethylamine, 48 μl (1.22 mmol) formic acid and 28 mg (0.024 mmol) tetrakis(triphenylphosphin)palladium(0) were added. The reaction mixture was stirred over night at room temperature. The reaction was diluted with approx. 20 ml water and twice extracted with approx. 20 ml dichloromethane. The combined organic phases were extracted with brine, dried over sodium sulfate and concentrated to dryness under reduced pressure. The raw product was purified by preparative RP-HPLC on a C18 column with a water/methanol gradient to yield 167 mg (65% of theory) product.

Provenance & Evidence