Methyl chloroformate → Carbonic acid 3-(2,5-dimethyl-phenyl)-8-methoxy-2-oxo-1,8-diaza-spiro[4.5]dec-3-en-4-yl ester methyl ester

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Reaction Conditions

Reaction Steps

To a solution of 200 mg of 3-(2,5-dimethyl-phenyl)-4-hydroxy-8-methoxy-1,8-diaza-spiro[4.5]dec-3-en-2-one and 0.14 ml of ethyl diisopropyl amine in 2 ml of chlorobenzene was added a solution of 66 mg of methyl chloroformate in 0.5 ml of chlorobenzene at 50° C. After stirring for 1 hour at 50° C., the reaction mixture was cooled to room temperature, diluted with 5 ml of chlorobenzene and washed with cold 5% aqueous sodium hydroxide and water. The organic phase was separated, dried over sodium sulfate, filtered and evaporated. The residue was purified by flash chromatography on silica gel. Yield: 120 mg of carbonic acid 3-(2,5-dimethyl-phenyl)-8-methoxy-2-oxo-1,8-diaza-spiro[4.5]dec-3-en-4-yl ester methyl ester (title compound A1). This material was triturated with ethyl acetate/hexane, filtered and dried to afford a solid, mp: 186-188° C.

Provenance & Evidence