[Synthesis]
Example 173 Synthesis of 2-(2-bromo-5-methyl-1,3-thiazol-4-yl)ethanol
To a solution of methyl 2-(2-bromo-5-methylthiazol-4-yl)acetate (3.80 g, 15.2 mmol) prepared in Example 172 in dichloromethane (100 mL) was slowly added diisobutylaluminum hydride (DIBAL-H, 33.4 mL, 33.4 mmol, 1.0 M toluene solution) at -78°C. After 15 min of reaction, the reaction system was slowly warmed to 0 °C and stirring was continued for 90 min. Subsequently, 2N aqueous hydrochloric acid solution (50 mL) was added dropwise to quench the excess DIBAL-H. The organic phase was separated and the aqueous phase was extracted with dichloromethane (2 x 200 mL). The organic layers were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. Purification of the residue by rapid column chromatography on silica gel (eluent ratio 5:2 hexane/ethyl acetate) afforded the target product 2-(2-bromo-5-methyl-1,3-thiazol-4-yl)ethanol (2.5 g, 74% yield) as a yellow oil, which solidified on standing.
Product characterization data:
Molecular formula: C6H8BrNOS
LC-MS: retention time 1.38 min, [M+H]+ m/z 221.0
1H NMR (CDCl3): δ 2.31 (s, 3H), 2.82 (t, 2H), 2.90-3.00 (wide s, 1H), 3.89 (t, 2H). |
[References]
[1] Patent: US2003/216391, 2003, A1
[2] Patent: US2018/153859, 2018, A1. Location in patent: Paragraph 0552; 0553
[3] Patent: US2018/153860, 2018, A1. Location in patent: Paragraph 0554; 0555 |