Selective oxidations of activated alcohols in water at room temperature.

Allylic and benzylic alcohols can be selectively oxidized to their corresponding aldehydes or ketones in water containing nanoreactors composed of the designer surfactant TPGS-750-M. The oxidation relies on catalytic amounts of CuBr, bpy, and TEMPO, with N-methyl-imidazole; air is the stoichiometric oxidant.

Efficient scavenging of Ph3P and Ph3P=O with high-loading merrifield resin.

[see reaction]. A simple, highly effective method for removing triphenylphosphine and/or triphenylphosphine oxide from reaction mixtures is described. Commercially available high-loading chloromethylated polystyrene 1, modified in situ with NaI, acts as a scavenger resin. Several coupling reactions catalyzed by Pd(0) or Ni(0) which require the removal of triphenylphosphine are tested.

New chiral crown ether stationary phase for the liquid chromatographic resolution of alpha-amino acid enantiomers.

A new chiral stationary phase (CSP) for the liquid chromatographic separation of enantiomers was prepared by bonding a novel enantiopure (diphenyl-substituted 1,1'-binaphthyl) crown ether to 5 microm silica gel. The resulting CSP was applied to the separation of the enantiomers of various natural and unnatural alpha-amino acids. All alpha-amino acids tested were resolved very well on the new CSP, with the exception of proline, which does not contain a primary amino group. The resolution of alpha-amino acid enantiomers on this new CSP was found to be dependent on the type and amounts of organic and acidic modifiers, and on column temperature.

Selective cleavage of Cbz-protected amines.

Under conditions of catalytic Ni(0) and in most cases just over 1 equiv of Me(2)NH.BH(3)/K(2)CO(3) or Cs(2)CO(3), a Cbz-protected nitrogen, which is part of a heteroaromatic ring, can be chemospecifically cleaved without affecting a Cbz group on an originally basic amine. [reaction: see text]

Mechanism of action of the marine natural product stypoldione: evidence for reaction with sulfhydryl groups.

Stypoldione, a marine natural product that possesses an o-quinone functional group, has been shown to inhibit a variety of biological processes including cell division. We found that stypoldione binds covalently to sulfhydryl groups of thiol-containing compounds via addition of sulfur to the C-4' position of the quinone ring. We examined the ability of stypoldione to add to sulfhydryl groups of a number of thiol-containing substances, including glutathione, thiophenol, beta-mercaptoethanol, and the protein tubulin. We suggest that the biological actions of stypoldione may be caused by the addition of this compound to thiol groups of biological molecules.