of course vs course

of course is not a noun while course is a noun.

Word	Noun	Adjective	Verb	Adverb
of course	No	No	No	Yes
course	Yes	No	Yes	Yes

As adverbs, of course and course are synonyms defined as:

Other synonyms of of course include naturally.

of course (noun)	course (noun)
	a mode of action
	education imparted in a series of lessons or meetings
	facility consisting of a circumscribed area of land or water laid out for a sport
	(construction) a layer of masonry
	part of a meal served at one time
	a connected series of events or actions or developments
	a body of students who are taught together
	general line of orientation
	a line or route along which something travels or moves

of course (adverb)	course (adverb)
as might be expected	as might be expected