Novel intermediate, method for preparing the same and application thereof

A method for preparing the intermediate, wherein the method comprises the following steps:

• S1.
• providing a compound 18 and producing a compound 19 through removal reaction of a hydroxyl protection group R1, where R1 is a hydroxyl protection group I, where R is a secondary amine protection group;
• S2.
• producing a compound 20 through reduction reaction of the compound 19;
• S3.
• producing the intermediate I through cyclization reaction of the compound 20;
• a synthesis route of the compound 18 is as follows:
• where R2 is a hydroxyl protection group II, X is a halogen atom, R11 is a hydroxyl protection group I or a hydrogen atom, and R1 is a hydroxyl protection group I;
• when R11 is the hydroxyl protection group I, a synthesis method comprises the following steps:
• 1) providing a compound 15;
• 2) producing a compound 17 through removal of the hydroxyl protection group II from the compound 15;
• and
• 3) producing the compound 18 through intramolecular oxidative dearomatization Heck reaction of the compound 17;
• when R11 is the hydrogen atom, the hydroxyl protection group I is introduced into the compound 15, and then step 2) and step 3) are performed;
• in step 3), the intramolecular oxidative dearomatization Heck reaction is performed in the presence of a reaction reagent and an alkali;
• the reaction reagent is a ligand II and a transition metal catalyst II;
• the ligand II is selected from
• the transition metal catalyst II is PdCl2;
• the molar ratio of the compound 17 to the ligand II to the transition metal catalyst II to the alkali is 1:(0.05-0.5):(0.05-0.15):(2-4).