Uses
5-Methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine-2-carboxylic Acid Hydrochloride(720720-96-7
) is used as a reagent in the synthesis of N-(2-acylaminobenzyl or 2-acylaminoheterocyclylmethyl)thiophene-2-carboxamide derivatives as antithrombotics. It is also used as a reagent in the synthesis of diamide derivatives as FXa inhibitors. 5-Methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine-2-carboxylic Acid Hydrochloride is an intermediate for Edoxaban (E555520).
Preparation
2-Bromo-5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine p-toluenesulfonic acid salt (40.0 g) was mixed with 1N aqueous sodium hydroxide (200 mL) at room temperature, and the mixture was stirred for 30 minutes. The aqueous layer was extracted with toluene twice (400 mL), and the organic layers were combined. The combined organic layer was washed with 5% brine (200 mL), and was concentrated to 80 mL at an external temperature of 50 °C or lower under reduced pressure. A sample for water content measurement was taken from the resultant mixture. The sample of the concentrated mixture was subjected to water content measurement with Karl-Fischer Moisture Titrator, and the water content was found to be 0.0231% (on a weight-to-weight ratio). The remaining portion of the concentrated mixture after sampling was dissolved in anhydrous tetrahydrofuran (231 mL). After the system was purged with argon, the reaction mixture was cooled to an internal temperature of -30 °C or lower, and to the solution was added dropwise n-butyllithium (as 1.59 mol/L n-hexane solution, 61.7 mL) while the internal temperature was kept at or below -30 °C, followed by stirring at the same temperature for 1 hour. After passing carbon dioxide gas through the resultant mixture while the internal temperature was kept at or below -30 °C, the reaction mixture was stirred under carbon dioxide atmosphere for 1 hour. The resultant mixture was heated to an internal temperature of 15 °C, and methanol (193 mL) was added thereto, to thereby dissolve the precipitated solid, and concentrated hydrochloric acid (19.3 mL) was added dropwise thereto while the internal temperature was kept at or below 20 °C. The resultant mixture was cooled to an internal temperature of 10 °C or lower, and was stirred at the same temperature for 1 hour. The precipitated crystals were collected by filtration, and were washed with methanol (58 mL). The wet crystal was dried at room temperature under reduced pressure, to thereby give 21.20 g of the title compound
