| abstract |
The invention relates to a crystal form of a substituted tricyclic pyridone derivative and a preparation method thereof, in particular to a baloxavir intermediate 7-(benzyloxy)-3,4,12,12a-tetrahydro-1H Crystal form of ‑[1,4]oxazine[3,4‑c]pyrido[2,1‑f][1,2,4]triazine‑6,8 dione, obtained by solvent screening to obtain crystal form A , the crystal form is stable and not easy to agglomerate under high humidity conditions, and the product obtained by using the crystal form as a raw material for splitting has high chiral purity. |