CABELL.ANDREWS@BIONET-20.BIO.NET (Paul Andrews) (08/02/88)
Hello..............
I am attempting to reproduce the synthesis of 8-(alpha)-hydroxyriboflavin
according to the procedure of H. Ohkawa et al [J. Biol. Chem. 258, 5623-5628
(1983)]. It is reported to be a produced by straightforward hydrolysis
(6N HCl,reflux) of 8-(alpha)-bromoriboflavin, which in turn was produced by
bromination of tetracetylriboflavin. I can produce the bromo derivative
easily enough (as confirmed by NMR) but hydrolysis under a variety of
conditions appears to produce only riboflavin again (assayed by reverse phase
HPLC). The authors report the hydroxy derivative was obtained in about 25%
yield after isolation by paper chromatography (eeeeeek!).
I may try an alternate route to the 8-hydroxy by making the 8-dibromo
compound, hydrolysing it to the 8-formyl and then reducing to the 8-hydroxy
with something like NaBH4. However, I would like to keep things as simple as
possible (ie, as few steps as possible) because I am eventually going to
produce the C14 labelled analogue of the 8-OH riboflavin and want to keep my
overall yield as high as possible. Has anyone out there evre attempted this
route, or have any ideas of what is going on with the hydrolysis in the
initial step?
Thanks....
Paul Andrews
CABELL.ANDREWS@BIONET-20.ARPA
-------