Was this category 1-4 award something you got by using points to get it? I am not aware of this type of award availability by using points. I am only aware of being able to get a free night category 1-4 stay by earning it through some promotion (such as a stay 2 nights, get a free night promo) or by spending a certain amount of money on the Chase Marriott Visa ($25,000 I believe is the amount).
When an award is earned through a promo or spending deal they must be used by the expiration date and I am not aware of any way they can be converted into points.
If you call customer service or send them an e-mail through the Marriott.com site, I am sure they will be able to give guidelines on your request.
Good luck and hope this helps.