Lawesson's reagent → (5R)-3-(3,4-dihydro-4-methyl-3-thioxo-2H-1,4-benzothiazin-7-yl)-2-oxo-5-oxazolidinecarboxylic acid methyl ester

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Reaction Steps

To a stirred suspension of the (5R)-3-(3,4-dihydro-4-methyl-3-oxo-2H-1,4-benzothiazin-7-yl)-2-oxo-5-oxazolidinecarboxylic acid methyl ester (EXAMPLE 62, Step 5, 1.26 g, 3.907 mmol) in dry dioxane (25 mL) is added Lawesson's reagent (2.37 g, 5.861 mmol). This reaction mixture is heated at 70–80° C. for 1.5–2 h at which time the reaction is cooled to room temperature and concentrated under reduced pressure. The residue is washed with EtOAc (15 mL×3), sonicated and filtered to give the title compound as a yellow solid (1.18 g, 89%), MS (m/z): 339.5 [M+H]+.

Provenance & Evidence