Abstract
We report a photocatalytic oxidation procedure that can be used
to convert benzylamines into their corresponding aldehydes under
mild conditions without over-oxidation, using riboflavin tetraacetate
as photocatalyst and blue emitting LEDs (440 nm) as light source.
Oxygen is the terminal oxidant and H2 O2 and
NH3 appear as the only byproducts of the oxidation of
primary benzylamines. Furthermore, we have developed a photocatalytic
protocol for 4-methoxybenzyl (Mob) group deprotection of primary
amines and alcohols. Double bonds, benzyl-protected esters and alcohols
are tolerated under the applied conditions, whereas the deprotection
of protected secondary amines is not applicable. Mob-protected carboxylic
acids and carboxybenzoyl (Cbz) protected amines are inert under
the photodeprotection conditions.
Key words
flavin - photooxidation - redox chemistry - electron transfer - benzyl protecting group
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