Yes, you can directly weld these material combinations, safe ending is not required. The filler metal can be either an E70xx (carbon steel) or an E80xx B2 (1.25Cr-1/2Mo) to match either the carbon steel or i.25Cr- 1/2Mo base material, respectively.
Don't forget to use preheat requirements for the F11 pipe base material and, if required, follow the post weld heat treatment requirements for the F11.