Post-cycloaddition modifications

Fluorous aminoesters have been employed in 3-component 1,3-dipolar cycloaddition reactions and post-condensation modifications in the synthesis of a bridged-tricyclic ring system 30 (Scheme 21) [49]. 

Likewise, Hirao et al. applied copper free chck chemistry for RNA functionalization via the 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds) and pyrrole-2-carbalde-hyde (Pa) unnatural base pair [152], For this, an azide-modified Pa nucleobase (N3-Pa) was incorporated as triphosphate in a T7 in vitro transcription reaction using Ds as corresponding nucleobase in the DNA template (Fig. 3b, 2). Post-transcriptional modification was achieved using fluorescent dibenzocyclooctyne (DIBO) derivatives in a strain-promoted azide-alkyne cycloaddition reaction. Transcription and efficient site-specific labeling of a 260mer RNA was demonstrated. 

Post-Synthetic Modification of Double-Pillared MOFs by [2+2] Cycloaddition Reaction... 

Post-synthetic modification of double-piUared MOFs by [2+2] photo-cycloaddition was demonstrated in the following examples. Three photo-reactive double-pillared MOFs, [Zn2(bpe)2(muco)2]-DMF-H20 (44), [Zn2(bpe)2(bdc)2] DMF (45), and [Zn2(bpe)2 (fum)2]-H20 (46) (H2muco = trans,trans-macomc acid, H2bdc = 1,4-benzene dicarboxylic acid, and H2fum = fumaric acid), have been investigated [53]. In these stmctures, the layer is formed by the [Zn2(02C-C)4 SBU in which each... 

In this chapter, various photochemical reactions involving CPs and MOFs have been described. These include structural transformations, post-synthetic modification of surfaces to create reactive sites, radicals which are not possible by convention synthetic routes, polymerization on the surfaces, and cis-trans isomerization of the guest molecules in the cavities using the dynamic behavior of the structures. Further, [2+2] cycloaddition reaction has been used as a tool... 

Post-polymerization modification of reactive polymer films provides the possibility to design complex coatings associated with intricate structure and morphology [1, 4, 97, 98]. Using a simple procedure, two or more types of chemical functionalities can be applied onto substrates that are contained in covalently grafted polymer films. Multifunctional surfaces can be fabricated by sequential click reactions or simultaneous multiple click reactions in one-pot. Click-like reactions such as thiol-based additions, activated ester coupling, and azide-alkyne cycloadditions are those most used for post-polymerization modification, because these reactions yield orthogonal reactive polymer brushes rapidly and quantitatively [17]. 

Pei Y, Moos WEI, Post-modification of peptoid side chains (3 + 2) cycloaddition of nitrile oxides with alkenes and alkynes on the solid-phase, Tetrahedron Lett., 35 5825-5828, 1994. 

Huisgen 1,3-dipolar cycloaddition (click reaction) between terminal alkynes and azides is a highly efficient approach for the post modification of polymers. This technique is tolerant to a wide rage of reaction conditions and functional groups allowing fast coupling reactions under simple reaction conditions with... 

Scheme 21 A dipolar cycloaddition-based post modification approach [74]...

Fig. 10 Huisgen cycloaddition (top) is one method of post-self-assembly modification, providing a means to decorate an SCC with a variety of pendant groups (bottom)...

Pore surface modification is the topic of current interest due to the ease in tuning the properties for different applications. Kitagawa and coworkers have used [2+2] cycloaddition reaction as a post-synthetic method to modify the pore structure... 

Pei1994 Pei, Y. and Moos, W.H., Post-Modification of Peptoid Side Chains [3+2] Cycloaddition of Nitrile Oxides with Alkenes and Alkynes on the Solid-Phase, Tetrahedron Lett., 35 (1994) 5825-5828. 

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