Oxidative stress is recognized as an important underlying factor in the
pathogenesis of many degenerative diseases as well as normal senescence. The
free radicals, reactive oxygen species (ROS) and electrophiles produced during
oxidative stress are capable of modifying nucleic acids, lipids and proteins. There
are a variety of oxidative modifications...
Four strategies which involve synthetic elaboration of
the shikimate nucleus are discussed. Methyl shikimate was
differentially protected as the 3,4-0-cyclopentylidene ketal
and as the 5- 0- tert- butyldiphenylsilyl ether. The methyl
ester was then reduced with diisobutylaluminum hydride and
the resulting allylic alcohol was oxidized to aldehyde 47
with pyridinium...
The first asymmetric synthesis of (-)-7-epicylindrospermopsin via intramolecular nitrone cycloaddition is described. The synthesis utilized a convergent approach to prepare the cycloaddition precursor 176, which was assembled by condensation of hydroxylamine 175 with aldehyde 145. Hydroxylamine 175 was synthesized from ethylene glycol (166) in seven steps. Aldehyde 145 was completed...
The ethyl acetate extract of the culture filtrate of the marine Ascomycete,
Leptosphaeria oraemaris (Linder) yielded a novel metabolite
designated by the common name leptosphaerin. An x-ray crystallographic
structure analysis was disproved by the synthesis of 3-acetoxy-S-(1,2-dihydroxyethyl)-
3-pyrrolin-2-one 1, starting with N,N-dibenzylhydroxylamine
47 and D-mannitol 44. Oxidation of 47 followed...
Various hypervalent iodine compounds were evaluated as reagents
for intramolecular phenolic oxidative coupling. It was found that
phenyliodine(III) bis(trifluoroacetate) was effective for the coupling
of the monophenolic substrate 13a to 14a under neutral conditions.
Vanadium oxytrifluoride and hypervalent iodine compounds were compared
as oxidants for the conversion of 32 to...