Alkyne cycloaddition, photo

F. 10 Schematic representation for the photo-affinity-based ABPP strategy. The structure of HDAC photo-crosslinking probe (SAHA-BPyne) is shown in the middle [115]. ABPP activity-based protein profiling, HDAC histone deacetylase, SAHA suberoylanilide hydroxamic acid, CuAAC copper(l)-catalyzed azide-alkyne cycloaddition, LC-MS/MS liquid chromatography-tandem mass spectrometry... 

From the cycloaddition reaction standpoint, the photo-generated reactive species suitable for both 1,3-dipolar cycloaddition reactions and Diels-Alder reactions have been studied in the literature. In this review, we will focus our discussion on four cycloaddition reactions (1) 1,3-dipolar cycloaddition between aUcenes and photogenerated nitrile imines (2) 1,3-dipolar cycloaddition between aUcenes and photogenerated nitrile ylides (3) photoinduced hetero Diels-Alder reactions and (4) photoinduced strain promoted azide-alkyne cycloaddition (Scheme 3). It is... 

Fig. 1 Cycloaddition reactions employed in nucleic acid labeling with reporter groups (green star). A Cu -mediated azide-alkyne cycloaddition (CuAAC) of a terminal alkyne with an azide. B Strain-promoted azide-alkyne cycloaddition (SPAAC) of an azide with a cyclooctyne derivative. C Staudinger ligation of an azide with a phosphine derivative (not a cycloaddition reaction, see below). D Norbornene cycloaddition of a nitrile oxide as 1,3-dipole and a norbornene as dipolarophile. E Inverse electron-demand Diels- Alder cycloaddition reaction between a strained double bond (norbornene) and a tetrazine derivative. F Photo-cUck reaction of a push-pull-substituted diaiyltetrazole with an activated double bond (maleimide)...

Generation of chemical patterns with photoreactive polymers photo-Diels-Alder surface anchoring followed by azide-alkyne click reaction to immobilize fluorescent dyes, (a) SPAAC strain-promoted azide-alkyne cycloaddition and (b) CuAAC Cu(l)-catalyzed azide-alkyne cycloaddition. (Source Adapted with permission from Reference [36d].)... 

The intramolecular 2 + 2-photo-cycloadditions of optically active allenesilanes (5) with enones and enoates produce silyl-substituted exo-methylenecyclobutanes (6) in high enantiometric excess. Photo-desilation leads to the parent unsaturated exo-methylenecyclobutanes (7) (Scheme 3).19 The cycloaddition of naphthoquinone to allyltrimethylsilane in the presence of Me2 A1C1 yields the expected 2 + 2-cycloadduct that slowly rearranges to the 2 + 3-adduct.20 hi the presence of bases, Cephalosporin triflates (8) undergo 2 + 2- and 4 + 2-cycloaddition with alkenes, alkynes, and dienes via an intermediate six-membered cyclic allene (9) (Scheme 4).21... 

An oxete has been characterized as the product of low-temperature irradiation of benzaldehyde with but-2-yne (equation 83), and on warming it gives the normal unsaturated ketone . A second product (29) appears on prolonged low-temperature irradiation as a result of cycloaddition of a second molecule of benzaldehyde to the oxete. With aldehydes and terminal alkynes the photocycloaddition reaction is in competition with photo-induced radical addition processes (see equations 36 and 37). 

Irradiation of the reaction mixture with UV-Vis light (350-500 nm), or sunlight enabled the reaction to be carried out at room temperature. The photochemistry process provided improved chemoselectivity by avoiding the homocyclotrimerization for the alkynes. For example, photo-catalyzed [2 + 2 + 2]-cycloaddition of various nitriles with acetylene at room temperature in the presence of CpCo(COD)2 provided the corresponding 2-pyridines such as 271 in 3-4 h in good to excellent yields. ... 

The Pauson-Khand reaction has also been carried out under different conditions, such as the use of chiral ligands, including PuPHOS, CamPHOS, and camphorsultam the use of aldehydes as the carbon monoxide source > the use of solid-supported cobalt catalyst to enhance purification, such as the dry-state adsorption the use of colloidal cobalt nanoparticle and the use of metallic cobalt supported on mesoporous silica prepared by decomposing Co2(CO)8 on mesoporous silica supports (SBA-15 and MCM-41) in the refluxing toluene solution.Other modifications include different promoting methods, such as photo-irradiation, microwave irradiation, molecular sieves, TEMPO,A-oxides, and supercritical fluids. Furthermore, the cycloaddition between allene and carbon monoxide under similar conditions is known as the allenic Pauson-Khand reaction,27,41 jjjg reaction among alkyne, carbodiimide, and CO is referred to as the aza-Pauson-Khand reaction. ... 

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