You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R)-N-[4-[6-(2-chloro-4-fluorophenyl)imidazo[2,1-b][1,3]oxazol-5-yl]pyrimidin-2-yl]-1-azabicyclo[2.2.2]octan-3-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H20ClFN6O
assistant