Oracle SQL Developer: Copy paste tables, with 2 different instances, with different table structure

Here I have 2 difference instances, one is called DEV and one is called SIT2. I created a public database link, called DBLINKSIT2(Basically just to create a bridge between DEV and SIT2) and I need to copy all(make a backup) the tables from DEV to SIT2, with additional filtration and joining with another table called LKUP.CTL_RWA_VERSION Below is the syntax that I have that is running in DEV.

begin       
    for r in (select DISTINCT TABLE_NAME from all_tab_columns where owner = 'DDSHIST' and COLUMN_NAME = 'SNAPSHOT_DT')      
      loop      
      begin     
       execute immediate     'INSERT INTO ||r.table_name|| @DBLINKSIT2
                          select a.* 
                          from DDSHIST.||r.table_name|| a  
                          INNER JOIN LKUP.CTL_RWA_VERSION b ON a.SNAPSHOT_DT = b.SNAPSHOT_DT and a.DDS_VERSION = b.DDS_VERSION 
                          WHERE b.GOLDEN_COPY = 'N'';   
       exception when others then null; 
      end;
      end loop;     
    end;

I put COLUMN_NAME = 'SNAPSHOT_DT' because some of the tables do not contain this column. So the joining condition is both SNAPSHOT_DT are the same, and DDS_VERSION are the same, WHERE golden copy in LKUP table = 'Y'. then loop the script, and insert into @DBLINKSIT2.

But I can't get the script to run and I don't know where I am getting this wrong.

Any help would be appreciated. Thank you.