Method for preparing compound as PI3K inhibitor and intermediate compound for preparing same

A method for preparing a compound of formula 6, the method comprising:

• reacting a compound of formula 5 with dimethylformamide-dimethylacetal in a polar aprotic solvent:
• wherein in above formulas 5 and 6, X1 and X4 are each independently a halogen atom, and
• in above formula 6, any one of R1 and R2 is a hydrogen atom and other is dimethylamine.

A method for preparing a compound of formula 7, the method comprising:

• subjecting a compound of formula 6 to a cyclization reaction:
• wherein in above formulas 6 and 7, X1 and X4 are each independently a halogen atom, and
• in above formula 6, any one of R1 and R2 is a hydrogen atom and other is dimethylamine.

A compound represented by formula 6 below:

• wherein in above formula 6, X1 and X4 are each independently a halogen atom, and
• any one of R1 and R2 is a hydrogen atom and other is dimethylamine.