3-(2-Bromo-1-oxopropyl)-spiro[2H-1,3-benzoxazine-2,1'-cyclohexan]-4(3H)-one

40033-95-2

563-76-8

158299-05-9

Comparative Example 1: 1.4,80 g of spiro[benzo[e][1,3]oxazine-2,1'-cyclohexyl]-4(3H)-one, 127 g of 2-bromopropionyl bromide, and 40 g of pyridine (molar ratio 1:1.6:1) were dissolved in chlorobenzene (mass ratio 1:4.4). The mixture was placed in a four-necked flask under nitrogen protection and reacted at 50 °C for 8 hours. After completion of the reaction, the mixture was washed three times with 200 g of water, three times with 200 g of 10% potassium hydroxide solution and three times with 200 g of water, in that order. The organic phases were combined and concentrated under reduced pressure to remove the solvent to obtain a colorless liquid. To this liquid was added 80 g of ethanol (mass ratio 1:1), cooled to -5 °C, stirred for 2 h, filtered and dried to give 109 g of 3-(2-bromo-1-oxopropyl)-spiro[2H-1,3-benzoxazine-2,1 '-cyclohexyl]-4(3H)-one. The molar yield was 84.5% and the purity was 97.9%.