Connected to Oracle Database 18c Express Edition Release 18.0.0.0.0 
Connected as user1@DBOFFICEXE

SQL> 
SQL> WITH
  2    TMain AS (SELECT '100 200 300 400 500' AS str
  3              FROM DUAL),
  4    TMain_parsed as (
  5  SELECT regexp_substr(str, '[^   ]+', 1, level) vvv
  6  FROM TMain
  7  CONNECT BY NVL(regexp_instr(str, '[^ ]+', 1, level), 0) <> 0
  8  )  /* -select vvv from Tmain_parsed*/
  9  select * from Tmain_parsed
 10  pivot
 11  (
 12   min(vvv)
 13   for vvv in (
 14               100, 200, 300, 400
 15                --select vvv from Tmain_parsed
 16              )
 17  );

100                                                                          200                                                                          300                                                                          400
---------------------------------------------------------------------------- ---------------------------------------------------------------------------- ---------------------------------------------------------------------------- ----------------------------------------------------------------------------
100                                                                          200                                                                          300                                                                          400

SQL>