1220330-11-9

Step 2: (0533) To a solution of tetrahydrofuran (THF, 3 mL) of the compound from Step 1 (110 mg, 0.60 mmol) was added an aqueous solution of lithium hydroxide (LiOH) (2 M, 0.90 mL, 1.8 mmol). The reaction mixture was stirred at room temperature for 1 hour. Upon completion of the reaction, the reaction solution was adjusted to pH 1 with 1 M hydrochloric acid (HCl, aq.) The aqueous layer was extracted with ethyl acetate (EtOAc, 3 × 3 mL). The organic layers were combined, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure to give 5-ethoxypyrazine-2-carboxylic acid (75 mg, 74% yield).

[1] Patent: US2015/307465, 2015, A1. Location in patent: Paragraph 0533
[2] Patent: WO2011/9898, 2011, A1. Location in patent: Page/Page column 99
[3] Patent: US2012/190672, 2012, A1. Location in patent: Page/Page column 30
[4] Patent: WO2012/98213, 2012, A1. Location in patent: Page/Page column 61