Lithium hydroxide, monohydrate → 2-Isopropyl-5-methylthiazole-4-carboxylic acid

Temperature

20 °C

A solution of lithium hydroxide monohydrate (0.2 g) in water (3 mL) was added to a solution of methyl 2-isopropyl-5-methylthiazole-4-carboxylate (example 69, step a) (0.5 g) in methanol (7 mL) and the reaction mixture was stirred at 20° C. for 3 hours. The methanol was removed under reduced pressure and the remaining aqueous solution was washed with ethyl acetate. The aqueous layer was acidified by dropwise addition of concentrated aqueous HCl and this mixture was extracted with ethyl acetate. The organic layer was dried over sodium sulphate, filtered and the solvent was removed under reduced pressure. The resultant gum crystallised on standing. Trituration with a mixture of isohexane (4 mL) and ether (1 mL) afforded the subtitled compound. Yield 0.160 g.

1. customThe methanol was removed under reduced pressure
2. washthe remaining aqueous solution was washed with ethyl acetate
3. additionThe aqueous layer was acidified by dropwise addition of concentrated aqueous HCl
4. extractionthis mixture was extracted with ethyl acetate
5. dry with materialThe organic layer was dried over sodium sulphate
6. filtrationfiltered
7. customthe solvent was removed under reduced pressure
8. customThe resultant gum crystallised
9. additionTrituration with a mixture of isohexane (4 mL) and ether (1 mL)

ORD record

ord-bbc550280048438f89e0e49ea4075707

Source dataset

uspto-grants-2012_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08148373B2