The Quran doesn’t have any one verse that talks about praying 5 times. Remember, while the Quran does provide a lot of details in some cases, it’s more like a ‘policy’ with details in Ahadith. But it has verses related to (1) the obligation of salat, and (2) reference to the various times of day. For example, Surah Hud, verse 114 states that “And establish prayer at the two ends of the day and at the approach of the night.” Similarly, there are other verses. However, the Quran along with Hadith together is used by the scholars to define the number and times of salat. Here is a good article that explains this in detail.