In theory you can, but it will be better if you do it after you get PR.
If you apply now, HO will first examine your PR application, and if you have qualified for PR, then only (if one year has passed since you acquired PR) they will approve your naturalisation.
So, in my opinion, there is no point in applying for naturalisation right now. Just be patient, and wait for PR confirmation. This way you will have piece of mind that you will not loose a fortune if you naturalisation is refused.
There is a further point that you should know. Once you get PR, then if you apply one year after the date of PR confirmation, then you will not have to supply any documents regarding your previous immigration status ie your status before PR.
If you apply before clocking one year from PR confirmation, then you will have to submit each and every document that you submitted for PR application. That gives another chance for HO to find problems in your previous applications.
Best of the best way would be, to wait for PR, and then wait one year after that, and then apply for naturalisation.
Patience will go a long way in getting a favourable outcome. Better to wait a little and have a favourable outcome, rather than rushing and getting some nasty surprise.
regards
