Isobutyryl chloride → 8-Isobutyryloxy-6-oxo-5,6-dihydro-pyrido[2,3-b]pyrazine-7-carboxylic acid methyl ester
Reaction equation
[CH3:1][O:2][C:3]([C:5]1[C:14](=[O:15])[NH:13][C:8]2=[N:9][CH:10]=[CH:11][N:12]=[C:7]2[C:6]=1[OH:16])=[O:4].[C:17](Cl)(=[O:21])[CH:18]([CH3:20])[CH3:19]>ClCCCl>[CH3:1][O:2][C:3]([C:5]1[C:14](=[O:15])[NH:13][C:8]2=[N:9][CH:10]=[CH:11][N:12]=[C:7]2[C:6]=1[O:16][C:17](=[O:21])[CH:18]([CH3:20])[CH3:19])=[O:4]Participants
4
Procedure
To a suspension of 8-hydroxy-6-oxo-5,6-dihydro-pyrido[2,3-b]pyrazine-7-carboxylic acid methyl ester (Example 7.1) in 1,2-dichloro-ethane (9 ml) was added powdered molecular sieves (4A) followed by dropwise addition of isobutyryl chloride (0.048 ml). The reaction mixture was heated to reflux for 5 hours, cooled to ambient temperature and filtered. The filtrate was concentrated to give 8-isobutyryloxy-6-oxo-5,6-dihydro-pyrido[2,3-b]pyrazine-7-carboxylic acid methyl ester as a light brown solid (0.166 g) which was used without further purification.