Lawesson's reagent → (R)-5-(5-bromo-2-fluoro-phenyl)-5-methyl-morpholine-3-thione

Participants

Reaction Conditions

Reaction Steps

A pressure tube was charged with a solution of N—[(R)-1-(5-bromo-2-fluoro-phenyl)-2-hydroxy-1-methyl-ethyl]-2-chloro-acetamide (2.00 g, 6.9 mmol) in tetrahydrofuran (50 ml). The colorless solution was treated with Lawesson's reagent (2.81 g, 6.9 mmol) to give a yellow suspension. The tube was sealed and the mixture stirred at 70° C. overnight. For the workup, the reaction mixture was diluted with ethyl acetate (300 ml) and extracted with a saturated solution of sodium hydrogen carbonate (75 ml). The organic layer was washed with brine (2×80 ml). The combined aqueous layers were extracted with ethyl acetate (300 ml). The combined organic layers were dried over sodium sulphate and concentrated at reduced pressure. The (R)-5-(5-bromo-2-fluoro-phenyl)-5-methyl-morpholine-3-thione was obtained as a light yellow gum (1.93 g, 92% of theory) sufficiently pure to be engaged in the next step without further purification. MS (ISP): m/z=302.0 [M+H]+, 304.0 [M+2+H]+.

Provenance & Evidence