Lithium Hydroxide → 2-Methyl-5,6-dihydro-4H-cyclopenta[d][1,3]thiazole-4-carboxylic acid

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Reaction Steps

To a solution of 31.5 g (149 mmol) of ethyl 2-methyl-5,6-dihydro-4H-cyclopenta[d][1,3]thiazole-4-carboxylate from step A in a mixture of 450 mL of anhydrous THF and 100 mL of methanol was added a solution of 149 mL of a 1.0 M solution (149 mmol) of lithium hydroxide. The resulting mixture stirred at room temperature for 3 h and then the volatile organics were evaporated in vacuo. The aqueous residue was extracted with Et2O (2×250 ml.) and then acidified to pH=3 with 170 mL of a 1.0 N hydrochloric acid solution. The solution was saturated with solid sodium chloride and then extracted with dichloromethane (3×250 mL). The combined organic layers were dried over magnesium sulfate, filtered and evaporated in vacuo. The crude residue was then triturated with acetonitrile, filtered and dried under vacuum to give the title compound as an off white solid. 1HNMR (500 MHz, CDCl3) δ: 11.75 (br s, 1H), 4.02 (m, 1H), 3.00 (m, 1H), 2.90-2.66 (m, 6H).

Provenance & Evidence