Buck converter with no datasheet questions
The C2300 is known as a bootstrap capacitor, it's used to drive switching mosfet gate above the VCC - Otherwise you'd have voltage dropout equal to the gate threshold voltage. 

The other two components are not possible to know for sure without a datasheet and rest of the (legible) schematic. I'd hazard PMID are capacitors for the internal switching circuitry and Q2301 is probably a signal for "power good" condition after the voltages have stabilized. Might be tied to ENable somewhere.