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439-03-2 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 439-03-2 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,3 and 9 respectively; the second part has 2 digits, 0 and 3 respectively.
Calculate Digit Verification of CAS Registry Number 439-03:
62 % 10 = 2
So 439-03-2 is a valid CAS Registry Number.

439-03-2Relevant articles and documents

Synthesis of the Thomsen-Friedenreich-antigen (TF-antigen) and binding of Galectin-3 to TF-antigen presenting neo-glycoproteins

Elling, Lothar,Hayes, Marc R.,Hoffmann, Marius,Pietruszka, J?rg

, (2020)

The Thomsen-Friedenreich-antigen, Gal(β1–3)GalNAc(α1-O-Ser/Thr (TF-antigen), is presented on the surface of most human cancer cell types. Its interaction with galectin 1 and galectin 3 leads to tumor cell aggregation and promotes cancer metastasis and T-cell apoptosis in epithelial tissue. To further explore multivalent binding between the TF-antigen and galectin-3, the TF-antigen was enzymatically synthesized in high yields with GalNAc(α1-EG3-azide as the acceptor substrate by use of the glycosynthase BgaC/Glu233Gly. Subsequently, it was coupled to alkynyl-functionalized bovine serum albumin via a copper(I)-catalyzed alkyne-azide cycloaddition. This procedure yielded neo-glycoproteins with tunable glycan multivalency for binding studies. Glycan densities between 2 and 53 glycan residues per protein molecule were obtained by regulated alkynyl-modification of the lysine residues of BSA. The number of coupled glycans was quantified by sodium dodecyl sulfate polyacrylamide gel electrophoresis and a trinitrobenzene sulfonic acid assay. The binding efficiency of the neo-glycoproteins with human galectin-3 and the effect of multivalency was investigated and assessed using an enzyme-linked lectin assay. Immobilized neo-glycoproteins of all modification densities showed binding of Gal-3 with increasing glycan density. However, multivalent glycan presentation did not result in a higher binding affinity. In contrast, inhibition of Gal-3 binding to asialofetuin was effective. The relative inhibitory potency was increased by a factor of 142 for neo-glycoproteins displaying 10 glycans/protein in contrast to highly decorated inhibitors with only 2-fold increase. In summary, the functionality of BSA-based neo-glycoproteins presenting the TF-antigen as multivalent inhibitors for Gal-3 was demonstrated.

A Substituent-Directed Strategy for the Selective Synthesis of L-Hexoses: An Expeditious Route to L-Idose

See, Nicholas W.,Wimmer, Norbert,Krenske, Elizabeth H.,Ferro, Vito

, p. 1575 - 1584 (2021/03/03)

L-Hexoses are rare but biologically significant components of various important biomolecules. However, most are prohibitively expensive (if commercially available) which limits their study and biotechnological exploitation. New, efficient methods to access L-hexoses and their derivatives are thus of great interest. In a previous study, we showcased a stereoselective Bu3SnH-mediated transformation of a 5-C-bromo-D-glucuronide to an L-iduronide. We have now drawn inspiration from this result to derive a new methodology – one that can be harnessed to access other L-hexoses. DFT calculations demonstrate that a combination of a β-F at the anomeric position and a methoxycarbonyl substituent at C-6 is key to optimising the selectivity for the L-hexose product. Our investigations have also culminated in the development of the shortest known synthetic route to a derivative of L-idose from a commercially available starting material (45 % yield over 3 steps). Collectively, these results address the profound lack of understanding of how to synthesise L-hexoses in a stereoselective fashion.

Open-Shell Fluorination of Alkyl Bromides: Unexpected Selectivity in a Silyl Radical-Mediated Chain Process

Lovett, Gabrielle H.,Chen, Shuming,Xue, Xiao-Song,Houk,MacMillan, David W. C.

, p. 20031 - 20036 (2019/12/27)

We disclose a novel radical strategy for the fluorination of alkyl bromides via the merger of silyl radical-mediated halogen-atom abstraction and benzophenone photosensitization. Selectivity for halogen-atom abstraction from alkyl bromides is observed in the presence of an electrophilic fluorinating reagent containing a weak N-F bond despite the predicted favorability for Si-F bond formation. To probe this surprising selectivity, preliminary mechanistic and computational studies were conducted, revealing that a radical chain mechanism is operative in which kinetic selectivity for Si-Br abstraction dominates due to a combination of polar effects and halogen-atom polarizability in the transition state. This transition-metal-free fluorination protocol tolerates a broad range of functional groups, including alcohols, ketones, and aldehydes, which demonstrates the complementary nature of this strategy to existing fluorination technologies. This system has been extended to the generation of gem-difluorinated motifs which are commonly found in medicinal agents and agrochemicals.

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