Ethyl 2-cyclopentyl-4,5-dihydrothiazole-4-carboxylate → Ethyl 2-cyclopentylthiazole-4-carboxylate

Manganese dioxide (24 g) was added to a solution of ethyl 2-cyclopentyl-4,5-dihydrothiazole-4-carboxylate (example 59, step b) (3.2 g) in acetonitrile (100 mL) and the resulting mixture heated at reflux overnight. The reaction was allowed to cool and filtered through a pad of Celite. The filter pad was washed with acetonitrile (2×100 mL) and the combined filtrate and washings evaporated. The residue was purified by silica gel chromatography eluting with 9:1 isohexane:ethyl acetate. The fractions containing product were combined, evaporated and redissolved in ethanol (20 mL). A slurry of palladium on carbon (5%, 0.66 g) in water (0.5 mL) was added and the resulting suspension stirred under an atmosphere of hydrogen at 5 bar pressure for 2 h. The mixture was filtered through a pad of Celite which was washed with ethanol (3×50 mL). The combined filtrate and washings were evaporated to give the subtitled compound as a clear oil. Yield 0.9 g.

1. temperaturethe resulting mixture heated
2. temperatureat reflux overnight
3. temperatureto cool
4. filtrationfiltered through a pad of Celite
5. washThe filter pad was washed with acetonitrile (2×100 mL)
6. customthe combined filtrate and washings evaporated
7. customThe residue was purified by silica gel chromatography
8. washeluting with 9:1 isohexane
9. additionThe fractions containing product
10. customevaporated
11. dissolutionredissolved in ethanol (20 mL)
12. additionA slurry of palladium on carbon (5%, 0.66 g) in water (0.5 mL) was added
13. filtrationThe mixture was filtered through a pad of Celite which
14. washwas washed with ethanol (3×50 mL)
15. customThe combined filtrate and washings were evaporated

ORD record

ord-9d96b972ed574ec1aeca2cb634850044

Source dataset

uspto-grants-2014_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08629271B2