Synthesis of quaternary amino acids bearing a (2'Z)-fluorovinyl alpha-branch: potential PLP enzyme inactivators

Protected alpha-formyl amino acids, themselves available from the corresponding alpha-vinyl amino acids, are stereoselectively transformed into the (Z)-configured alpha-(2'-fluoro)vinyl amino acids via a three-step sequence. The route employs McCarthy's reagent, diethyl alpha-fluoro-alpha-(phenylsulfonyl)methyl phosphonate, and proceeds via the intermediate (E)-alpha-fluorovinyl sulfones and (E)-alpha-fluorovinylstannanes. The latter may either be exploited as novel cross-coupling partners for fluorovinyl branch extension or be globally deprotected, to provide the title compounds. [structure: see text]     

An improved error bound for a finite element approximation of a model for phase separation of a multi-component alloy

Using the approach of Rulla (1996 SIAM J. Numer. Anal. 33, 68-87)for analysing the time discretization error and assuming moreregularity on the initial data, we improve on the error boundderived by Barrett and Blowey (1996 IMA J. Numer. Anal. 16,257-287) for a fully practical piecewise linear finite elementapproximation with a backward Euler time discretization of amodel for phase separation of a multi-component alloy.     

A facile synthesis of simple alkaloids—synthesis of 2,3-polymethylene-4(3H)-quinazolinones and related alkaloids

An efficient procedure for preparation of the simple alkaloids, 2,3-polymethylene-4(3H)-quinazolinones, luotonin A, tryptanthrin, and rutaecarpine has been established by the reaction of lactam-HCl salts with POCl₃ followed by cyclization with methyl anthranilate.     

Characterization of in vitro metabolites of rutaecarpine in rat liver microsomes using liquid chromatography/tandem mass spectrometry

Following incubation of rutaecarpine, a new cyclooxygenase-2 inhibitor, with rat liver microsomes, the structures of the metabolites were characterized by liquid chromatography with tandem mass spectrometry. Nine metabolites corresponding to mono- or dihydroxylated rutaecarpine were formed. Characteristic product ions for the identification of rutaecarpine metabolites were observed at m/z 136, 158 and 286. The loss of water led to the fragment ion at m/z 286, indicating the hydroxylation of the aliphatic ring. The fragment ion at m/z 136 indicated the hydroxylated form of the phenyl group of the quinazolinone moiety, while that at m/z 158 indicated the hydroxylated form of the aromatic ring of the indole moiety.     

Finite element approximation of a model for phase separation of a multi-component alloy with a concentration-dependent mobility matrix

We consider a model for phase separation of a multi-componentalloy with a concentration-dependent mobility matrix and logarithmicfree energy. In particular we prove that there exists a uniquesolution for sufficiently smooth initial data. Further, we provean error bound for a fully practical piecewise linear finiteelement approximation in one and two space dimensions. Finallynumerical experiments with three components in one space dimensionare presented.