[mana]

hi
is this mechanism correct? honestly I can't understand why the second step will occur, I mean what is the driving force here?

[sjb]

Look into things like the Pictet-Splengler - https://en.wikipedia.org/w/index.php?title=Pictet%E2%80%93Spengler_reaction&oldid=812126988

Having said that, it may not be correct but it's the best available interpretation of what's going on we have as far as I know.

[clarkstill]

Attack of the (extremely electron rich) arene onto the imine (or iminium, under acidic conditions) seems pretty plausible. However, the subsequent step (which forms the ortho quinone) is an oxidation. You haven't drawn it, but a hydride must be lost if you want to form the product drawn.

I'd imagine that in the absence of an oxidant the next step would be rearomatization (as is the case with most electrophilic aromatic substitutions), by re-forming the catechol: