Synthesis of human ultraviolet filter compounds: O-β-D- glucopyranosides of 3-hydroxykynurenine and 2-amino-3-hydroxy-γ- oxobenzenebutanoic acid

The role of endogenous tryptophan-derived UV filters in aging lenses and in human cataract is becoming increasingly important. The two major UV filters found in the lenses of primates, the O-β-D-glucopyranosides of 3- hydroxykynurenine and 2-amino-3-hydroxy-γ-oxobenzenebutanoic acid, 1 and 2, were synthesized from the common benzoyl acrylate precursor 2-amino-3- hydroxybenzoylacrylic acid 10. Synthesis of compound 3, the α-N-acetyl derivative of 1, was achieved using coupling of 2-nitro-3- benzyloxyacetophenone 4 with the sodium salt of diethyl acetamidomalonate as a key step. This is the first reported synthesis of the lenticular glucopyranoside 2 and the N-acetyl compound 3.