A curious benzenoid deacylation reaction: neighbouring group participation in acylhydroxy[2.2]paracyclophanes

Attempted carbonyl reduction of acyldihydroxy[2.2]paracyclophanes with sodium borohydride led instead to competing aromatic deacylation. The effect was traced to a neighbouring group participation that can be correlated with carbonyl IR stretching frequencies. Deuterium labelling studies implicate the formal intermediacy of a solvated [2.2]paracyclophane anion via an SE1 mechanism.