4-Methoxybenzyl alcohol → 4-Methoxybenzyl {(1R)-1-[(R)-{[tert-butyl(dimethyl)silyl]oxy}(phenyl)methyl]pent-4-yn-1-yl}carbamate

Participants

Reaction Conditions

Reaction Steps

To a solution of 40.0 g (120 mmol) of (2R)-2-[(S)-{[tert-butyl(dimethyl)silyl]oxy}(phenyl)methyl]hex-5-ynoic acid from Step D above and 33.5 mL (241 mmol) of triethylamine in 400 mL of anhydrous toluene at ambient temperature under an atmosphere of nitrogen was added 37.5 mL (132 mmol) of diphenylphosphoryl azide. The mixture was stirred for 5 h and then 37.5 mL (301 mmol) of 4-methoxybenzyl alcohol was added. The resulting mixture was heated to 105° C. for 16 h, cooled to ambient temperature and then diluted with 250 mL of a saturated aqueous bicarbonate solution. The phases were separated and the aqueous phase was extracted with ethyl acetate (2×150 mL). The combined organics were washed with water (100 mL), brine (100 mL) then dried over magnesium sulfate, filtered and evaporated in vacuo. The crude residue was purified by silica gel chromatography eluting with 3-10% ethyl acetate in hexanes to afford the title compound as a colorless oil (50.9 g, 90.5%). 1H NMR (500 MHz, CDCl3): 7.28-7.21 (m, 7H), 6.87 (d, J=8.4 Hz, 2H), 4.92 (s, 2H), 4.77-4.59 (m, 2H), 3.89-3.84 (m, 1H), 3.81 (s, 3H), 2.30-2.22 (m, 2H), 1.95 (m, 1H), 1.91-1.85 (m, 1H), 1.57-1.50 (m, 1H), 0.89 (s, 9H), 0.06 (s, 3H), −0.15 (s, 3H). LC-MS: m/z (ES) 468.1 (MH)+, 490.0 (MNa)+.

Provenance & Evidence