Synthesis
GENERAL STEPS: A dichloromethane (100 ml) solution of 4-dimethylaminopyridine (2.55 g, 21.3 mmol) and triethylamine (46.9 ml, 340.8 mmol) was slowly added to a dichloromethane (300 ml) solution of (S)-4-benzyl-2-oxazolidinone (37.7 g, 213 mmol) at 0 °C. Subsequently, a solution of isovaleryl chloride (33.75 ml, 207 mmol) in dichloromethane (50 ml) was added dropwise while keeping the internal temperature below 10 °C. The reaction mixture was stirred at 10 °C for 30 min and then filtered to remove the formed salt. Water (100 ml) was added to the filtrate for phase separation. The organic phase was washed sequentially with water (100 ml) and brine (100 ml), dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give 53 g of a yellow oily product, which solidified to a solid on standing (95% yield). The product was characterized by 1H NMR (300 MHz, CDCl3, 298 K) and 13C NMR (75 MHz, CDCl3, 298 K) and confirmed to be the target compound 3-isopentanoyl-4(R)-benzyl-2-oxazolidinone.
References
[1] Helvetica Chimica Acta, 2012, vol. 95, # 10, p. 1937 - 1945,9
[2] Patent: WO2011/151442, 2011, A2. Location in patent: Page/Page column 24
[3] Patent: US2013/71899, 2013, A1. Location in patent: Paragraph 0124-0127
[4] Journal of Medicinal Chemistry, 2016, vol. 59, # 23, p. 10530 - 10548
[5] Organic Process Research and Development, 2015, vol. 19, # 6, p. 611 - 617
