2-((tert-butyldiphenylmethylsilyl)oxy)acetic acid (7.34 g, 23.3 mmol) and N,O-dimethylhydroxylamine hydrochloride (6.83 g, 69.9 mmol) were dissolved in dichloromethane (20 mL) at room temperature. A solution of N,N'-dicyclohexylcarbodiimide (DCC, 14.4 g, 69.9 mmol) in dichloromethane (23 mL) was slowly added to the mixture, followed by heating and refluxing until the feedstock was completely consumed (monitored by thin layer chromatography). After the reaction mixture was cooled to room temperature, the reaction was quenched by the addition of water and extracted with ethyl acetate (3 x 30 mL). The organic phases were combined, dried with anhydrous magnesium sulfate, concentrated under reduced pressure and purified by fast column chromatography (eluent: ethyl acetate/hexane, 30:70). 2-((tert-butyldiphenylmethylsilyl)oxy)-N-methoxy-N-methylacetamide (7.10 g, 85% yield) was obtained as white crystals. Melting point: 53.4-54.8 °C. 1H NMR (400 MHz, CDCl3): δ 7.74-7.72 (m, 4H), 7.42-7.37 (m, 6H), 4.43 (s, 2H), 3.43 (s, 3H), 3.13 (s, 3H), 1.10 (s, 9H). 13C NMR (100 MHz, CDCl3 ): δ 180.4, 135.5, 133.1, 129.8, 127.7, 62.0, 61.2, 32.5, 26.7, 19.4. FT-IR (KBr): 1691 cm-1 (C=O). Mass spectrum (m/z): 300.4 (M+ - tBu). Elemental analysis calculated values (%): C, 67.19; H, 7.61; N, 3.92. measured values (%): C, 67.30; H, 7.23; N, 4.30.
