Nsc group

VV Samukov, AN Sabirov, PI Pozdnyakov. 2-(4-Nitrophenyl)sulfonylethoxycarbonyl (Nsc) group as a base-labile a-amino protection for solid phase peptide synthesis. Tetrahedron Lett 35, 7821, 1994. 

Alternative base-labile protecting groups such as the 2-[4-nitrophenyl)sulfonyl]ethoxy-carbonyl (Nsc) group have been developed to face the problems arising with the Fmoc group. These are discussed in Section 2.1.1.1.1.4. 

One major advantage for employment of the Nsc annino acids is that they are potentially less expensive to manufacture than Fmoc annino adds, a crucial factor when large-scale production is under consideration. However, the general utility of the Nsc group still has to be proven over a wide range of synthetic objectives before it can be widely accepted. 

This derivative was prepared from the chloroformate (88-90% yield) and can be cleaved with piperidine. It is expected to be more labile to base than the Nsc group. 

The Tsc group was developed as a more soluble alternative to the Nsc group for the protection of pyrrole-imidazole polyamides. It is formed from the 4-nitrophenyl... 

The NsC groups coordinated in the axial position to the iron atom of the porphyrin fragment undergo a decrease in the spin transfer from the iron in a H-bonding solvent, and the paramagnetic shift is reduced. 

Few reports are available for systematic approaches towards new selective inhibitors of DNMTs. The most prominent example is the tryptophan derivative RG108 (NSC401077) that was identified via a virtual screening approach [30, 82] and is active between 10 and 100 iM. In the same study, NSC 303530 was also identified as a somewhat weaker inhibitor (Figure 8.10). The analog of R108 that does not contain the carboxylic acid group was found to be inactive. 

The Moura group propose the formation of a stable cyano-bridged diiron derivative following ferricyanide oxidation of the superoxide reductases (SORs) from Treponema pallidum and from Desulfovibrio vulgaris.10 Spectroscopic evidence for a ferrocyanide adduct with the bridge (SOR)Fe-NsC-Fen(CN)5 came from mass and IR measurements, where the Fe co-ordination is made up of four equatorial histidine N atoms and an axial cysteinyl S atom, and it is proposed... 

Knowing the viscosity and density of the reaction mixture, the flow channel diameter, void fraction of the bed, and the superficial fluid velocity, it is possible to determine the Reynolds number, estimate the intensity of dispersion from the appropriate correlation, and use the resulting value to determine the effective dispersion coefficient Del or I). Figures 8-32 and 8-33 illustrate the correlations for flow of fluids in empty tubes and through pipes in the laminar flow region, respectively. The dimensionless group De l/udt = De l/2uR depends on the Reynolds number (NRe) and on the molecular diffusivity as measured by the Schmidt number (NSc). For laminar flow region, DeJ is expressed by ... 

In our group we have used SA in lattice 2D and 3D KMC in order to identify key parameters for parameter estimation from experimental data (see corresponding section below). Finite difference approximations of NSC were employed (Raimondeau et al., 2003 Snyder and Ylachos, 2004). Drews et al. (2003a) motivated by extraction of parameters for Cu electrodeposition, obtained an expression for the sensitivity coefficient, analogous to Eq. (9), that minimizes the effect of noise on the NSC assuming that the variance of the stochastic correction is unaffected by the perturbation. 

The 2-[(4-nitrophenyl)sulfonyl]ethoxycarbonyl group (Nsc, 27) has been developed as an alternative to the Fmoc group for solid-phase peptide synthesis,t 9 to counter certain shortcomings of the Fmoc/tBu strategy such as the insufficient stability of N -Fmoc-pro-tected amino acids and peptides in weakly basic conditionst 1 and unfavorable hydro-phobic interactions and steric hindrance of the bulky Fmoc group. 

Also the relatively polar nature and hence greater solubility of Nsc compared to the Fmoc group may offer benefits when aggregation becomes a problem in the peptide chain. 

Protocols for use of the Nsc amino acids are essentially the same as those described for Fmoc derivatives, but because of the increased stability to base, longer exposure to 20% piperidine/ DMF is required (5 min and 10 min) to effect complete removal of the group. Otherwise the cycle is the same as above and nominally all of the side-chain protecting groups available in Fmoc chemistry can be applied with Nsc chemistry. A recent comparative study of the... 

Malfetano JH, Blessing JA, Homesley HD. A phase n trial of gallium nitrate (NSC 15200) in nonsquamous ceU carcinoma of the cervix. A Gynecologic Oncology Group Study. Am J Clin Oncol 1995 18(6) 495-7. 

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