Disulfide chemistry/bond/functional group

For a review of 1,3-dipolar addition to other double bonds, see Bianchi, G. De Micheli, C. Gandolfi, R., in Patai, S. Supplement A The Chemistry of Double-Bonded Functional Groups, pt. 1, Wiley, NY, 1977, pp. 369-532. For a review of such addition to the C=S bond, see Dunn, A.D. Rudorf, W. Carbon Disulfide in Organic Chemistry, Wiley, NY, 1989, pp. 97-119. 

Covalently immobilized arrays are formatted by glycans with functionalized spacers that react with a complementary activated surface to form a covalent bond. Several different covalent interactions were reported to construct a specified glycan array. Amine chemistry and thiol chemistry are the two major methods to conjugate glycans to the reactive substrate in the array surface (Fig. 15.2). Thiol chemistry was first adapted by Injae Shin in 2002 to react with the maleimide functional group (Fig. 15.2a, b) [7,41 ]. Disulfide bond formation was then reported for the fabrication... 

The small-molecule-based machine conceived by von Delius, Geertsema, and Leigh [45] is a linear (for reviews, see [46], [100]) motor based on dynamic covalent chemistry [19-24] (forming, breaking, and reforming of dynamic covalent bonds with relatively fast equilibration in response to stimuli), namely on acyl-hydrazone and disulfide exchanges. The motor consists of a track that has four functional groups disposed alternately aldehyde-thiol-aldehyde-thiol which are the positions 1,2, 3, and 4 of the track, a walker NH2-NH-CO-(CH2)5-SH which has the feet A (hydrazide or acyl-hydrazine) and B (thiol), and a placeholder with a foot C of type thiol (Fig. 10). 

Many of the chemical properties of thiols stem from the fact that the sulfur atom of a thiol is oxidized easily to several higher oxidation states. The most common reaction of thiols in biological systems is their oxidation to disulfides, the functional group of which is a disulfide (—S—S —) bond. Thiols are readily oxidized to disulfides by molecular oxygen. In fact, they are so susceptible to oxidation that they must be protected from contact with air during storage. Disulfides, in turn, are easily reduced to thiols by several reagents. This easy interconversion between thiols and disulfides is very important in protein chemistry, as we will see in Chapter 18 ... 

The functional group tolerance of the ruthenium-based metathesis catalysts has had a tremendous impact on solid-phase organic synthesis. The efficacy of the reaction in solution generally translates directly to solid-phase transformation and its potential has been harnessed in a number of library syntheses, solid-phase syntheses of natural products, or diversity-oriented syntheses. It enables the use of chemically robust alkenes as linkers which can be cleaved by RCM or CM. It, of course, provides new manifolds of diversification in diversity-oriented synthesis as has been elegantly shown in landmark examples by Schreiber and Nelson. Another metathesis application of paramount importance is in peptide chemistry where solid-phase synthesis is omnipresent. The ability to stabilize secondary structures in short peptide motifs and replace pharmacologically unsuitable disulfide bonds or simply restrict the conformation of a peptidic library has already been successfully implemented in a number of important examples. The orthogonality of the metathesis reaction to peptide chemistry provides a really powerful tool in this regard. 

Various click chemistries, building the foundation for most post-polymerization modifications, have also been applied for fabrication of reactive porous polymer monoliths [118-125]. Click reactions include alkyne-azide, thiol-ene, and thiol-yne reactions, and these reactions can be conducted under mild conditions, unlike many other polymer graft reactions. Svec and coworkers used the thiol-ene reaction to functionalize porous polymer monoliths [121]. Monoliths were thiolated with cysteamine, followed by cleavage of the disulfide bonds using tri(2-carboxylethyl) phosphine to expose the desired thiol groups. Then, lauryl methacrylate monomers were clicked onto the monoliths using either heat or UV initiation. Thiol-yne and... 

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