Is there a 12V stable output regulator for liion?
Well I do not want output to change because different input. I want stable 12v no matter battery level   


You can generate 12 V from boost regulator, even if the input voltage is varying.



Boost regulators generate output based on the set feedback voltage. It is not dependent on a integer multiple of input voltage. 

There are dedicated boost regulators for single lithium ion cell batteries whose output can be set anywhere from 5V to 18 V. You can start searching from here.. 

Please study about basics of buck and boost regulators too. There are many simple application notes and documents on it.