Photolysis of p-hydroxyphenacyloxy arenes releases free phenols in good yields governed by their pKa. At high pKa, new byproducts (Bvs. A) reveal a change in reaction mechanism.
Combining the fast thermal cyclization of o-coumaric acid derivatives with the intramolecular photoreduction of quinones gives new visible-light photoremovable protecting groups absorbing well above 450 nm.