Recently, I happened to find a problem that involved the synthesis of anthracene from bromobenzene in the presence of tert-butyl lithium, using THF as the solvent, and at room temperature. I am wondering the mechanism for this transformation.
Taking into account that THF degrades in tert-butyl lithium this is the one that I thought of,
It starts with aryne formation. Benzyne reacts with ethene in a [2+2] cycloaddition. This undergoes cycloreversion. The resulting product reacts with another mole of benzyne to create the dihydro-derivative. This reacts with another equivalent of tert-butyl lithium to form anthracene.
I have a question regarding this. I do not think a cycloreversion could occur at room temperature (wiki gives a temperature of 180 degrees and states that the conrotary opening is unfavored). Is this the case or not? Am I missing another possible mechanism here?