Triethylamine → 2-(t-Butyloxycarbonylamino)-4-(N-(Cbz-isoleucyl)amino)-1,5-diphenyl-3-hydroxypentane

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Reaction Steps

The resultant compound of Example 11 (125 mg, 0.34 mmol), N-benzyloxycarbonyl-isoleucine p-nitrophenyl ester (196 mg, 0.51 mmol) and triethylamine (94 μL, 0.67 mmol) were combined with 1.0 mL of dry THF and stirred together at ambient temperature overnight. The reaction mixture was then heated at reflux temperature for 3 h. The cooled reaction mixture was then diluted with 5 mL of THF and 5 mL of 3M aqueous sodium hydroxide solution was added. The mixture was stirred at ambient temperature for approximately 0.5 h. and was then diluted with chloroform. The chloroform solution was washed with 3×25 mL of 0.5M aqueous sodium hydroxide solution and brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The residue (227 mg) was taken up in approximately 5 mL of chloroform and applied to a 1.0×45 cm column of 40 mesh silica gel. The column was eluted @ 5-10 p.s.i. sequentially with 100 mL of chloroform, 100 mL of 0.5% methanol in chloroform and 100 mL of 1% methanol in chloroform to give 169 mg (81% yield) of the title compound; FAB MS M/Z: 618 (M+H)+. The 300 MHz 1H NMR spectrum was consistent with the assigned structure.

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