SQL> create table test (some_date date);

Table created.

SQL> insert into test (some_date)
  2    values (to_date('20140501130926', 'yyyymmddhh24miss'));

1 row created.

SQL> alter session set nls_date_format = 'dd.mm.yyyy hh24:mi:ss';

Session altered.

SQL> select * from test;

SOME_DATE
-------------------
01.05.2014 13:09:26

SQL>

SQL> SELECT to_date(20140501130926, 'yyyymmdd h24:mi:ss') FROM dual;
 
SELECT to_date(20140501130926, 'yyyymmdd h24:mi:ss') FROM dual
 
ORA-01821: date format not recognized

SQL> --add missing h.
SQL> SELECT to_date(20140501130926, 'yyyymmdd hh24:mi:ss') FROM dual;
 
TO_DATE(20140501130926,'YYYYMM
------------------------------
20140501 13:09:26
 
SQL>