The selective visible-light-driven generation of a weak
acid (sulfinic
acid, in nitrogen-purged solutions) or a strong acid (sulfonic acid,
in oxygen-purged solutions) by using shelf-stable arylazo sulfones
was developed. These sulfones were then used for the green, smooth,
and efficient photochemical catalytic protection of several (substituted)
alcohols (and phenols) as tetrahydropyranyl ethers or acetals.