\chemfig{
            H% 8
     -[:180]% 1
    =_[:240]% 2
               (
         -[:300]H% 9
               )
     -[:180]% 3
               (
         -[:240]H% 10
               )
    =_[:120]% 4
               (
         -[:180]O% 7
         -[:120]H% 13
               )
      -[:60]% 5
               (
         -[:120]H% 11
               )
          =_% 6
               (
         -[:300]% -> 1
               )
      -[:60]H% 12
}
