1-Methyl-4-(2-thienyl)-1,2,3,6-tetrahydropyridine → 3,3,3-Trifluoro-2-(trifluoromethyl)-1,2-propanediol

Beteiligte Stoffe

Reaktionsschritte

A glass 3-L four-neck flask was fitted with a mechanical stirrer, a Dimroth condenser, and a dropping funnel. Operating at room temperature, 1 L of pure water was introduced into the reactor followed by the introduction of 69 g (1.93 mol) sodium tetrahydroborate and dissolution. To this was added dropwise 515 g (2.28 mol) 2-hydroxy-3,3,3-trifluoro-2-trifluoromethylpropionic acid methyl ester (MTTHP). Suitable cooling was performed with ice water during this period so as to prevent the liquid temperature from exceeding 50° C. After the dropwise addition of all of the MTTHP, stirring was performed for 1 hour at room temperature and quenching was carried out by the dropwise addition of 300 mL 35% aqueous hydrochloric acid into the reaction solution on an ice bath. The quenched solution was subjected to suction filtration to remove the salts produced during the reaction and the residual salt was washed twice with 500 mL isopropyl ether (IPE). The obtained filtrate was separated and the organic layer was recovered and the aqueous layer was extracted twice with 700 mL IPE. The organic layer and the extracts were combined and dried over magnesium sulfate; suction filtration was performed and the filtrate was recovered; and the IPE was removed by condensation on an evaporator. Simple distillation of the resulting solution under reduced pressure yielded 217 g (isolated yield=48%, purity=98%) 3,3,3-trifluoro-2-trifluoromethylpropane-1,2-diol.

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