Hello, everyone. Seeking an explanation as to the effect of oxygen presence during synthesis/reaction. From the outline of forum rules, preference to just discuss the mechanism itself involving as little information as possible regarding the procedure or products will be followed. Any info to increase understanding would be greatly appreciated!
During acid/solvent re flux of compund A, compound B is formed from transition of hydroxyl group to pyran ring. Oxygen presence or extended heat/reaction time causes a double bond shift from the 9th carbon to the 8th carbon to form compound C.
The goal is to understand the mechanism oxygen is causing when present.