91183-17-4

Step 3: Compound 10c (8.9 g, 40 mmol) was added to 100 mL of phosphorus oxychloride (POCl3) and heated to reflux for 5 hours. Upon completion of the reaction, some of the phosphorous trichloride was removed by distillation. The reaction mixture was quenched by careful pouring into ice water. The pH of the mixture was adjusted to 7-8 with ammonia at a temperature below 10 °C. Subsequently, the mixture was extracted with ethyl acetate. The organic phases were combined, dried with anhydrous sodium sulfate and the solvent was concentrated under reduced pressure to give the target product 10d (1.7 g, 16.7% yield). Mass spectrometric analysis showed [M + H]+ of 255.1.

[1] Patent: EP2754659, 2014, A1. Location in patent: Paragraph 0168; 0173; 0174
[2] Patent: US2014/378488, 2014, A1. Location in patent: Paragraph 0380; 0385; 0386