Hydrochloric Acid → (S)-benzyl 2-((2R,6R)-2,6-dimethyltetrahydro-2H-pyran-4-yl)-2-(methoxycarbonylamino)acetate

Participants

Reaction Steps

(S)-Benzyl 2-((2R,6R)-2,6-dimethyltetrahydro-2H-pyran-4-yl)-2-(diphenylmethyleneamino)acetate (Cap-2, step d.2) (129.6 mg, 0.294 mmol) was dissolved in THF (2 mL) and then treated with 2N HCl (1.0 mL, 2.1 mmol) in water. The reaction was stirred for 2 h and then concentrated under a stream of nitrogen overnight. The crude residue was dissolved in DCM (2 mL) and DIPEA (0.21 mL, 1.2 mmol) and then treated with methyl chloroformate (0.032 mL, 0.41 mmol) and stirred at RT for 4 h. The reaction was diluted with water (˜2.5 mL) and extracted with DCM (4×2 mL). The combined organic phase was concentrated under a stream of nitrogen overnight and the residue was purified with a Biotage® Horizon (4 g SiO2, 10-50% EtOAc/hexanes) to yield (S)-benzyl 2-((2R,6R)-2,6-dimethyltetrahydro-2H-pyran-4-yl)-2-(methoxycarbonylamino)acetate (Cap-2, step e) (56 mg) as a colorless glass. LC-MS retention time 3.338 min; m/z 335.99 [M+H]+. LC data was recorded on a Shimadzu LC-10AS liquid chromatograph equipped with a Phenomenex-Luna 3u C18 2.0×50 mm column using a SPD-10AV UV-Vis detector at a detector wave length of 220 nM. The elution conditions employed a flow rate of 0.8 mL/min, a gradient of 100% solvent A/0% solvent B to 0% solvent A/100% solvent B, a gradient time of 4 min, a hold time of 1 min, and an analysis time of 5 min where solvent A was 5% MeOH/95% H2O/10 mM ammonium acetate and solvent B was 5% H2O/95% MeOH/10 mM ammonium acetate. MS data was determined using a Micromass Platform for LC in electrospray mode. 1H NMR (400 MHz, D4-MeOH) δ ppm 7.29-7.42 (m, 5H), 5.28 (d, J=12.0 Hz, 1H), 5.09 (d, J=12.0 Hz, 1H), 4.10-4.20 (m, 2H), 3.68-3.78 (m, 1H), 3.65 (s, 3H), 2.22-2.36 (m, 1H), 1.42-1.54 (m, 2H), 1.29-1.38 (m, 1H), 1.17 (d, J=6.8 Hz, 3H), 1.04 (d, J=6.0 Hz, 3H), 0.89-1.00 (m, 1H).

Provenance & Evidence