p-Toluenesulfonic acid → Methyl 2-hydroxy-8-(4-methylthiazol-5-yl)octanoate

Participants

Reaction Steps

To a solution of (E)-methyl 2-(cyclohexyloxy)-8-(4-methylthiazol-5-yl)oct-7-enoate (560 mg, 1.58 mmol) and ethanol (40 mL) was added 10% palladium on carbon (82 mg) and the resulting mixture was hydrogenated at 1 atm H2 overnight. The resulting mixture was then filtered through CELITE and concentrated in vacuo to yield methyl 2-(cyclohexyloxy)-8-(4-methylthiazol-5-yl)octanoate (97%) which was used in the next step without further purification. A solution of methyl 2-(cyclohexyloxy)-8-(4-methylthiazol-5-yl)octanoate (563 mg, 1.58 mmol), methanol (8.6 mL), and p-toluenesulfonic acid (14.8 mg, 0.086 mmol) was stirred at room temperature for 1 h. Solvent was removed in vacuo to yield methyl 2-hydroxy-8-(4-methylthiazol-5-yl)octanoate which was used in the next step without further purification. A mixture of 2-hydroxy-8-(4-methylthiazol-5-yl)octanoic acid (590 mg, 2.17 mmol), tetrahydrofuran (21 mL), water (54 mL) and lithium hydroxide (78.1 mg, 3.26 mmol) was stirred at room temperature for 2 h. The resulting mixture was acidified with 1N HCl and concentrated in vacuo. An excess amount of acetonitrile was added to the residue and the mixture was concentrated. The process was repeated twice to yield 2-hydroxy-8-(4-methylthiazol-5-yl)octanoic acid which was used in the next step without further purification. MS (ES+) 258 (M+1).

Provenance & Evidence