Catalytic Effect of Thioles in Oxidation of the Vinyl Group to Aldehyde in Chlorophyll a Derivatives

Alternative synthesis of 3-acetyl, 3-epoxy, and 3-formyl chlorins from a 3-vinyl chlorin, methyl pyropheophorbide-a, via iodination

“…Conversion of the C3-vinyl group of methyl pyropheophorbide-a (1) into an acetyl (4), an epoxy(5), and a formyl group(6). Effects of amines to the reaction were also shown (5, 7, and 9 from 1).…”

“…The mechanism of formylation of the vinyl group in Chl-d biosynthesis has not yet been clarified, while it is thought that co-oxidation of the vinyl group with thiol and oxygen plays a key role in the transformation. [4][5][6][7][8][9] Various (B)Chl derivatives are also derived in vitro from methyl pyropheophorbide-a (1), a stable synthetic intermediate prepared from abundant Chl-a, through transformation of the C3-vinyl group. Hydrobromination and subsequent hydrolysis of 1 afforded the C3-(1-hydroxy)ethyl derivative.…”