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

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Reaction Steps

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.

Provenance & Evidence