Thank you for writing in here.
It sounds like your four year old really doesn't like these boys' behavior in his class.
He may be very stressed from their aggressive behavior.
level is worrisome.
He may need to learn how to cope with their behavior appropriately effectively.
If these boys are annoying him, he may need to know how to handle them.
You may ask his teacher how he is doing in class first.
It's very important for you parents to listen to his feelings, be empathetic to him,
and teach him how to deal with others' aggressive behavior.
Perhaps, he may need help from his teacher when his peers act out aggression.
I"ll pause here and await your response.
I"ll get off online soon and come back tomorrow.