Thionyl Chloride → 9-benzyloxy-2-(3-chlorobenzyl)-7-(2,2-dimethylbutyryl)-3,4-dihydro-2H-pyrido[1,2-a]pyrazine-1,8-dione

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Reaction Conditions

Reaction Steps

9-Benzyloxy-2-(3-chlorobenzyl)-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-7-carboxylic acid (200 mg) obtained in Example 219, Step 2 was suspended in tetrahydrofuran (6 ml), and triethylamine (0.07 ml) and thionyl chloride (0.037 ml) were added at room temperature with stirring. After stirring at room temperature for 10 min, the mixture was cooled to −78° C. and 1.0 M 1,1-dimethylpropylmagnesium chloride/ether solution was added dropwise. After further stirring at the same temperature for 20 min, 5% aqueous potassium hydrogen sulfate solution (5 ml) and ethyl acetate (6 ml) were added, and water (5 ml) was further added. The mixture was extracted twice with ethyl acetate-tetrahydrofuran (1:1, 30 ml each). The organic layer was dried and concentrated, and ethyl acetate was added to the residue. The obtained solid was collected by filtration to give 9-benzyloxy-2-(3-chlorobenzyl)-7-(2,2-dimethylbutyryl)-3,4-dihydro-2H-pyrido[1,2-a]pyrazine-1,8-dione (59 mg).

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