General procedure for the synthesis of 2-fluoro-3-nitrobenzyl alcohol from methyl 2-fluoro-3-nitrobenzoate:
1. DIBAL (115.7 mL, 1.0 M toluene solution) was slowly added to a toluene solution (92 mL) of methyl 2-fluoro-3-nitrobenzoate (9.22 g, 46.3 mmol) at -78 °C.
2. The reaction mixture was stirred at -78 °C for 30 min, then warmed to 0 °C and continued stirring for 30 min.
3. The reaction solution was cooled again to -78 °C and methanol, saturated Rochelle brine and ethyl acetate were added sequentially.
4. The mixture was transferred to room temperature, stirred for 1 hour and then extracted three times with ethyl acetate.
5. The organic layers were combined, washed with saturated brine and dried over anhydrous magnesium sulfate.
6. The organic phase was concentrated under pressure to give 2-fluoro-3-nitrobenzyl alcohol as a brown oil (7.52 g, 95% yield). 7. The product was analyzed by 1H NMR.
7. The product was confirmed by 1H NMR (CDCl3): δ 7.95 (m, 1H), 7.84 (t, 1H), 7.31 (t, 1H), 4.87 (s, 2H).
8. HPLC analysis: Rt = 7.52 min (conditions were the same as in the preparative embodiment of compound 3a-1).
