Lawesson's reagent → (R)-5-(5-bromo-2-fluoro-phenyl)-2,2,5-trimethyl-1,1-dioxo-1lambda6-thiomorpholin-3-thione

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Reaction Conditions

Reaction Steps

To a solution of (R)-5-(5-bromo-2-fluoro-phenyl)-2,2,5-trimethyl-1,1-dioxo-1λ6-thiomorpholin-3-one (1.4 g, 3.84 mmol, Eq: 1.00) in dioxane (29.5 ml) was added Lawesson's reagent (3.10 g, 7.68 mmol, Eq: 2.00). The reaction mixture was stirred at 80° C. for 10 hours. The reaction mixture was poured into sat. NaHCO3-solution and extracted twice with ethyl acetate. The organic layers were washed with brine, dried over Na2SO4, filtered and evaporated to give a light yellow oil. The residue was chromatographed on 20 g silica gel with ethyl acetate in heptane to give (R)-5-(5-bromo-2-fluoro-phenyl)-2,2,5-trimethyl-1,1-dioxo-1λ6-thiomorpholin-3-thione (1.3 g, 3.42 mmol, 88.9% yield) as a light yellow foam. MS (ISP): m/z=380.0 [M+H]+ and 382.3 [M+2+H]+.

Provenance & Evidence