I wanted to make a monthly segment (if possible) presenting a challenge to the chemistry community here on Brilliant. This will be the first (of hopefully many) challenge(s):
Furan is an aromatic heterocylic that is known to participate in pericyclic reactions. The most common way of preparing such a ring is through metal mediated cyclization reactions.
The following conversion has no additional reagents and the initial compound is mildly heated to obtain the product. The conversion involves three steps:
A mechanism can be either hand drawn or made using an online web tool. An answer will be provided in 96 hours (or earlier) if no one can provide a suitable mechanism.