Lawesson's reagent → (R)-8-(5-bromo-2-fluoro-phenyl)-8-methyl-6,6-dioxo-6lambda6-thia-9-aza-spiro[4.5]dec-2-en-10-thione

Participants

Reaction Conditions

Reaction Steps

A mixture of (R)-8-(5-bromo-2-fluoro-phenyl)-8-methyl-6,6-dioxo-6λ6-thia-9-aza-spiro[4.5]dec-2-en-10-one (410 mg, 1.06 mmol, Eq: 1.00) and Lawesson's reagent (427 mg, 1.06 mmol, Eq: 1.00) in dioxane (10 ml) was stirred at 80° C. for 2 hours. More Lawesson's reagent (427 mg, 1.06 mmol, Eq: 1.00) was added and stirring continued at 85° C. for 16 hours. More Lawesson's reagent (427 mg, 1.06 mmol, Eq: 1.00) was added and stirring continued at 95° C. for 6 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 light yellow oil. The residue was chromatographed on 20 g silica gel with dichloromethane/heptane to give (R)-8-(5-bromo-2-fluoro-phenyl)-8-methyl-6,6-dioxo-6λ6-thia-9-aza-spiro[4.5]dec-2-en-10-thione (305 mg, 754 μmol, 71.4% yield) as a light yellow foam. MS (ISP): m/z=404.1 [M+H]+ and 406.2 [M+2+H]+.

Provenance & Evidence