[Synthesis]
The general procedure for the synthesis of 2-((tert-butyldiphenylsilyl)oxy)acetic acid from methyl 2-((tert-butyldiphenylmethylsilyl)oxy)acetic acid was as follows: to a solution of methyl 2-((tert-butyldiphenylsilyl)oxy)acetic acid (8.86 g, 27.0 mmol) in THF/H2O (4:1, 33 mL) was added an aqueous 0.75 M LiOH solution ( 97 mL, 72.9 mmol). The reaction mixture was stirred at room temperature until thin layer chromatography (TLC) showed complete consumption of the feedstock. Upon completion of the reaction, water (appropriate amount) was added and the resulting mixture was extracted with ether (3 x 40 mL) to remove non-acidic impurities. The aqueous phase was acidified to pH 3 with 10% aqueous HCl and subsequently extracted with ethyl acetate (3 x 50 mL). The organic phases were combined, dried with anhydrous MgSO4, filtered and concentrated under reduced pressure to give the crude product. The crude product was confirmed for purity by nuclear magnetic resonance (NMR), which resulted in 2-((tert-butyldiphenylmethylsilyl)oxy)acetic acid (7.97 g, 94% yield) as a colorless oil. The structure of the product was determined by 1H NMR (400 MHz, CDCl3): δ 7.68-7.65 (m, 4H), 7.46-7.38 (m, 6H), 4.25 (s, 2H), 1.10 (s, 9H); 13C NMR (100 MHz, CDCl3): δ 174.9,135.5,132.9,130.2. 128.0,61.9,26.7,19.2; mass spectrum (M/z): 237.1 (M+-Ph); Fourier Transform Infrared Spectroscopy (FT-IR, thin film): 1737 cm-1 (C=O telescoping vibration); Calculated values for elemental analysis (%): C, 68.75; H, 7.05; Measured values (%): C, 68.70; H, 6.91. |
[References]
[1] Bioorganic and Medicinal Chemistry, 2011, vol. 19, # 3, p. 1236 - 1241
[2] Journal of the American Chemical Society, 2010, vol. 132, # 31, p. 10920 - 10934 |