Sodium triacetoxyborohydride → tert-butyl (5S,12S)-12-[(R)-[(3R,4R,5R)-3,4-bis{[tert-butyl(dimethyl)silyl]oxy}-5-(3-(4-methoxybenzyl)-2,4-dioxo-3,4-dihydro-1(2H)-pyrimidinyl)tetrahydro-2-furanyl](hydroxy)methyl]-5-[3-(tert-butoxy)-3-oxopropyl]-3,6-dioxo-1-phenyl-2-oxa-4,7,11-triazatridecan-13-oate

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Reaction Steps

By using an analogous procedure to that described for Example 1, a solution of tert-butyl (2S,3R)-2-amino-3-[(2R,3R,4R,5R)-3,4-bis{[tert-butyl-(dimethyl)silyl]oxy}-5-(3-(4-methoxybenzyl)-2,4-dioxo-3,4-dihydro-1(2H)-pyrimidinyl)-tetrahydro-2-furanyl]-3-hydroxypropanoate (100 mg, 0.139 mmol, obtained from Reference Example 6), tert-butyl (4S)-4-{[(benzyloxy)carbonyl]amino}-5-oxo-5-[(3-oxopropyl)amino]pentanoate (60 mg, 0.152 mmol, obtained from Reference Example 26), acetic acid (2 drops), and sodium triacetoxyborohydride (59 mg, 0.277 mmol) in anhydrous tetrahydrofuran (4 ml) was stirred under nitrogen at room temperature for 3.5 hours. The product was purified by chromatography (flash column, silica gel, 4% methanol in methylene chloride) to provide tert-butyl (5S,12S)-12-[(R)-[(3R,4R,5R)-3,4-bis{[tert-butyl(dimethyl)silyl]oxy}-5-(3-(4-methoxybenzyl)-2,4-dioxo-3,4-dihydro-1(2H)-pyrimidinyl)tetrahydro-2-furanyl](hydroxy)methyl]-5-[3-(tert-butoxy)-3-oxopropyl]-3,6-dioxo-1-phenyl-2-oxa-4,7,11-triazatridecan-13-oate (126 mg, 83%) as a white amorphous solid.

Provenance & Evidence