Phosphines azido

Synthesis of azindines Irom epoxides via amino alcohols or azido alcohols and reaction with phosphines or phosphites... 

Figure 11.22 Azido-sialic acid-containing glycans can be labeled in vivo with biotin-PEG-phosphine using the Staudinger ligation reaction, which forms an amide bond.

The methods used for in vivo incorporation of azido-monomers and performing a labeling reaction with live cells are relatively simple. The following protocol is based on the methods of Saxon and Bertozzi (2000), which uses acetylated azidoacetylmannosamine as the azido-monomer source and a biotin-PEG-phosphine compound to biotinylate cell surface glycoproteins at the specific azide-sialic acid incorporation sites (Figure 17.19). 

Add to the washed cells 60 pi of a 5 mM concentration of the phosphine derivative to couple to the azido-sugar groups on the cell surface (e.g., biotin-PEG-phosphine). 

Figure 17.19 An azido-sialic acid derivative that gets incorporated into glycans in cells can be labeled specifically with a biotin-phosphine tag using the Staudinger ligation process. The result is an amide bond linkage with the glycan.

Figure 17.20 An azido-palmitic acid derivative can be added to cells to obtain palmitoylated proteins that contain an azide group able to participate in the Staudinger ligation reaction. Biotinylation of these post-translationally modified sites then can be done in vivo using a biotin-phosphine reagent.

Figure 17.24 The traceless Staudinger reaction can be used to form larger peptides from smaller peptides, if one contains an azido group at the N-terminal and the other one contains a phosphine ester at its C-terminal. The reaction gives a native peptide (amide) bond with loss of the phosphine group.

Figure 18.11 NHS-PEG4-azide can be used to modify an amine-containing molecule to create an amide derivative terminating in azido groups. The azide modifications then can be used in a click chemistry reaction that forms a triazole linkage with an alkyne-containing molecule. Alternatively, the azide derivative can be used in a Staudinger ligation reaction with a phosphine derivative, which results in an amide bond linkage.

Thermolysis of organo azido phosphines produce organo cyclophosphazenes in high yields [25]. Recently, Guy Bertrand and coworkers have obtained a four membered cyclophosphazene [26-27] derivative, N2P2(NPr2)4 by photolyzing the corresponding azidophosphine (Eq. 12). 

It has been shown that coupling of the ethyl phosphinate A with 5 -azido-2 -methoxy-5 -deoxythymidine B to afford the corresponding phosphon-amidate proceeds with retention of configuration at the phosphorus atom. Determine the configuration of reactants and product. 

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