Facile synthesis of 1,4-benzothiazin-3-ones from Cu-catalyzed coupling of 2-iodoanilines and 2-mercaptoacetate

A novel synthesis of 1,4-benzothiazin-3-ones was developed from Cu-catalyzed coupling of readily available substituted 2-iodoanilines with 2-mercaptoacetate. The new method offers clear advantages over existing approaches for its one-step simple operation, wider reaction scope, and moderate to excellent isolated yields.     

Facile synthesis of 9-(arenethenyl)purines via Heck reaction of 9-vinylpurines and aryl halides

The first example of a Heck reaction with 9-vinylpurines and aryl halides is described. It gives exclusively E-9-(arenethenyl)purines in high yields. Subsequent hydrogenation furnishes 9-(arenethyl)purines quantitatively.     

A Src SH2 selective binding compound inhibits osteoclast-mediated resorption

BACKGROUND: The observations that Src(-/-) mice develop osteopetrosis and Src family tyrosine kinase inhibitors decrease osteoclast-mediated resorption of bone have implicated Src in the regulation of osteoclast-resorptive activity. We have designed and synthesized a compound, AP22161, that binds selectively to the Src SH2 domain and demonstrated that it inhibits Src-dependent cellular activity and inhibits osteoclast-mediated resorption. RESULTS: AP22161 was designed to bind selectively to the Src SH2 domain by targeting a cysteine residue within the highly conserved phosphotyrosine-binding pocket. AP22161 was tested in vitro for binding to SH2 domains and was found to bind selectively and with high affinity to the Src SH2 domain. AP22161 was further tested in mechanism-based cellular assays and found to block Src SH2 binding to peptide ligands, inhibit Src-dependent cellular activity and diminish osteoclast resorptive activity. CONCLUSIONS: These results indicate that a compound that selectively inhibits Src SH2 binding can be used to inhibit osteoclast resorption. Furthermore, AP22161 has the potential to be further developed for treating osteoporosis.     

Expeditious synthesis of C2- or N4-aryl-1,4-benzothiazin-3-one via orthogonal Pd-catalyzed C-arylation and Cu-catalyzed N-arylation

Direct, chemo-specific arylation at C-2 or N-4 of 1,4-benzothiazin-3-one with aryl halides, based on Pd or Cu catalyst system, respectively, provided easy entry to arylated derivatives, a class of molecules not easily accessible via existing methods. Under Pd-catalysis conditions with LiHMDS as the base, N-arylation of 1,4-benzothiazin-3-one was inhibited leading to Cα-arylation of a secondary amide without the need for protection and de-protection of more acidic amido NH.     

Size of the freeze-out source in high energy heavy ion collisions

Based on a hydro-inspired azimuthally symmetric emission function, we analyze the HBT radius Rs and the single-particle transverse momentum spectra in Au+Au collisions measured by the STAR Collaboration at SNN = 200 GeV. The results show that consistent assumptions about transverse density (and/or flow profile) in the calculation of the HBT radius Rs and single-particle spectral analyses play an important role for understanding the size of the freeze-out source.     

Periodic wavetrains for systems of coupled nonlinear Schrödinger equations

Exact, periodic wavetrains for systems of coupled nonlinear Schrödinger equations are obtained by the Hirota bilinear method and theta functions identities. Both the bright and dark soliton regimes are treated, and the solutions involve products of elliptic functions. The validity of these solutions is verified independently by a computer algebra software. The long wave limit is studied. Physical implications will be assessed.     

Problems in colour measurement of fluorescent paper grades

The paper industry's demand for high white paper products is increasing. This requires usage of well-bleached fibres and high dosage of fluorescent brightening agents (FBAs) often applied both in the wet end and at the size press. Specialty paper makers may also use fluorescent colourants for shaded grades, in combination with non-fluorescent colourants and sometimes FBAs. Thus there is an immediate need for reliable, repeatable and reproducible measurement of colour in fluorescent grades.

The paper industry uses a variety of spectrophotometers and colorimeters as their laboratory quality reference instruments. Unfortunately, even on non-fluorescent grades the agreement between different colour instruments is not at the level provided by measurements of properties such as weight or caliper. Furthermore, laboratory instruments measure a stack of sheets, while on-machine instruments measure a single layer, causing additional sources of instrument disagreement and quality deviations.

Colour target specifications and grade limits are usually supplied as colorimetric quantities. This is barely adequate for non-fluorescent grades and problematic for fluorescent grades. Moreover, the standard vocabulary for colour terms is ambiguous concerning certain phenomena relevant to measuring and controlling the colour of fluorescent samples.

This paper describes the special problems in colour measurement of fluorescent grades. Process and instrument issues are discussed. Ambiguities in standard terminology and practices are identified, and improvements are recommended. Examples are given with measurements made at several paper mills.