Dabco → HCID 13001869, compound

Participants

Reaction Conditions

Reaction Steps

To 30 ml. of DMF were added 2.73 grams (7.1 mmoles) of Nα -t-butyloxycarbonyl-Nα -methyl-O-benzyl-L-tyrosine (prepared by acidification of 3.6 grams of the product from Part A and extraction into ether). The solution was cooled to 0° C., and 2.26 grams (7.1 mmoles) of the tosylate salt of D-alanine, benzyl ester, were added followed by 0.794 grams (7.1 mmoles) of triethylenediamine. The mixture was stirred at 0° C. for five minutes, and 0.96 grams of HBT and 1.46 grams (7.1 mmoles) of DCC were added. The mixture was stirred at 0° C. for two hours and then at room temperature for 24 hours. The mixture then was cooled to 0° C. and filtered. The filtrate was concentrated in vacuo to an oil, and then the oil was dissolved in ethyl acetate and extracted successively with 1 N aqueous sodium bicarbonate, water, 1.5 N citric acid, and water. The organic phase was dried over magnesium sulfate and concentrated in vacuo to an oil. The oil was dissolved in 60 ml. of ethanol, and 1.5 grams of 5% palladium on carbon were added to the mixture as a water slurry. Nitrogen was bubbled into the reaction mixture through a gas dispersion tube for five minutes followed by hydrogen gas for 24 hours. The mixture was flushed with nitrogen, and the catalyst was removed by filtration. The reaction mixture was concentrated in vacuo to an amorphous solid to give 2.5 grams (99 percent) of the title compound.

Provenance & Evidence