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Click Chemistry (PDF File) Click Chemistry “Click Chemistry” is a term which was first described by K. B. Sharpless in 2001 to describe reactions that afford products in ● Research of Various Pharmaceutical high yields and in excellent selectivities by carbon-hetero bond Lead Candidates formation reactions. The term “Click” means joining molecular a) Application of Anti-HIV Agent Discovery 3) pieces as easily as clicking together the two pieces of a seat belt Whiting and Sharpless et al. have reported the synthesis of a buckle. In general, the definition of click chemistry is described as series of 1,4-disubstituted-1,2,3-triazoles as potential candidates follows: for HIV protease inhibitors in a combination of azide-containing fragments with a diverse array of functionalized alkyne- 1. give very high chemical yields of desired products containing building blocks by using click chemistry. After further 2. combination of readily available simple building blocks optimization, it was revealed that 1 has the highest activity, 3. generate almost no byproducts exhibiting 8 nM of Ki value. 4. simple product isolation by non-chromatographic methods O 5. reaction proceeds in water, as well as in organic solvents R HN O O (36 Alkynes) Ph R = N Cl Ph HN O CuSO4, Cu N Ph N t N While there are a number of reactions that fulfill this criteria, the Ph BuOH / H2O (1 : 1), N Ki = 23 nM (minimum) N3 50 C°, 5 days R Hüisgen 1,3-dipolar [3 + 2] cycloaddition1) of azides and alkynes has emerged as the frontrunner. In general, the 1,2,3-triazole ring O is not almost oxidized or reduced, which makes it possible to HN O Ph (CH2O)n Ph strongly connect two substrates. N CH2OH nBuLi, THF, -78 C° to 0 C° N N N N Ki = 8 nM Metal (cat.) Cl 1 Ligand N N N + + N N N b) Research of Mycobacterium Tuberculosis In the Hüisgen reaction, metal catalysts, such as copper sulfate, Cell Wall Synthetase4) are generally required for reaction acceleration. In especial, it has Dondoni et al. have reported the synthesis of a set of been reported that the combination of tris[(1-benzyl-1H-1,2,3- C-oligomannosides (2a-f) through click chemistry using a triazol-4-yl)methyl]amine (TBTA) [T2993] and catalysts shows 1,2,3-triazole ring as the interglycosidic linker. The compounds excellent reactivity.2) 2a-f inhibit mannosyltransferases, which are involved in the biosynthesis of the cell envelope of Mycobacterium tuberculosis cell wall synthase. Among them, the hexamer (n = 4) 2c and octamer (n = 6) 2f show the highest activities IC50 = 0.14 and N N N 0.22 mM, respectively. N N N N N N N HO N3 N3 H3C OBn OBn OBn OBn O O O O BnO BnO BnO BnO BnO BnO BnO BnO OMOM TBTA OH [T2993] H3C OH O This reaction system affords desired products in almost 100% HO HO yield with no need of repurification, such as recrystallization or N column chromatography. Thus, this methodology is an eco- NN OH O HO HO friendly reaction. Moreover, the combination of various alkynes n N and azides allows it to rapidly construct large compound libraries, 2a (n = 0) NN OH 2b (n = 2) O and 1,2,3-triazole itself exhibits various kinds of biological HO 2c (n = 4) HO activities, such as anti-allergenic or anti-bacterial activities. In 2d (n = 6) 2e (n = 8) addition, the reaction proceeds even in water, and thus, click OH 2f (n = 14) chemistry has been widely used in many research fields as below. 2 Please inquire for pricing and availability of listed products to our local sales representatives. Click Chemistry ● Synthesis of Functional Materials ● Copper-free Click Reaction Click chemistry has been also successfully applied into polymer As described above, click chemistry also has been used for synthesis or material science. For example, Kang and Jin et al. imaging labeling and tracking labeling of biomolecules. However, have reported the synthesis of side-chain liquid-crystal polymers 3 the reaction is not suitable for labeling of living systems because it and 4 by using click chemistry. According to their results, the dye- needs a highly-concentrated copper(I) species, thus, bioorthogonal sensitized solar-cell fabricated from 3 gives a power-conversion reactions such as metal-free click chemistry also have been efficiency of 4.11%.5) developed. N-(1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethyloxycarbonyl-1,8- diamino-3,6-dioxaoctane (BCN-amine) [B4062] is a linker having + R O(H C) O C CO (CH ) O R a strained structure with cyclooctyne, and it is used for the copper- N3 N3 2 6 2 2 2 6 C8H17 C8H17 free click reaction to azides. For example, B4062 bonded to a fluorophore (9) has resulted in labeling of an azidohomoalanine- 14) N containing virus capsid protein without copper(I) species. In CuSO ・5H O, Et N N N 4 2 3 3 N Na-L-ascorbate C8H17 C8H17 addition, B4062 can be applied to not only strain-promoted alkyne- THF n 15) R O(H2C)6O2C CO2(CH2)6O R azide cycloaddition (SPAAC) but also strain-promoted alkyne- 16) 3 (R = OMe) nitrone cycloaddition (SPANC). 4 (R = CN) O O H H ● Bioscience O + N O C Fluorophore 6) O NH2 Bioconjugation (example: surface modification of virus) O N O O H In general, viruses are made up of a number of protein subunits, [B4062] and capsids, which enclose DNA or RNA, are formed as protein shells. In particular, in the case of spherical viruses, the capsids have an icosahedral symmetry form with sixty protein subunits. H H O Finn and Sharpless et al. have reported the modification of the H O N Fluorophore O N O exterior surface of a spherical virus, cowpea mosaic virus by H O azides or alkynes, followed by the labeling of these species using 9 fluorescein dye-azide or alkyne by click chemistry. N N N NNN H H HO O O N N N 3 strain-promoted H H alkyne-azidecycloaddition O 60 H O O (SPAAC) O N Fluorophore O N O CO2H H Virus capsid 5 O H H N N CH3 O N R N O O 60 H O CH3 = - ) 7 (R C CH N 6 - 8 (R = CH2CH2N3) O H H strain-promoted O N H N alkyne-nitronecycloaddition O N Fluorophore O (SPANC) O N O Cu(I) N H 57+ HN O Dye n N N N Additionally, Hosoya et al. have reported the “double-click reaction” Cu(I) O 68+ HN applying 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene [T3241] Dye n 17) in click chemistry. The high reactivity of the two alkyne moieties allows the reaction to proceed smoothly without using metal Thus, click chemistry has been widely used as a methodology of catalysts, such as a copper salt.18) synthesizing novel molecules in a number of research fields. Other than these applications, click chemistry also has been applied in various fields, such as the synthesis of dendrimers,7) dendrons,8) calyxarenes,9) rotaxanes,10) catenanes,11) the development of chemical sensors,12) and the labeling of DNA.13) Please inquire for pricing and availability of listed products to our local sales representatives. 3 Click Chemistry TCI offers a variety of azide and terminal acetylene compounds Metal-Free Double-click Rection readily available in the field of click chemistry as below. In addition, N N N azidation and ethynylation reagents are also listed in this brochure. Ph Ph N N ● Azidation Reagent N Ph N3 Organic azide compounds can be synthesized in a simple manner + by the reaction of sodium azide with halogenated alkyl compounds, MeOH,rt N or the reaction with trifluoromethanesulfonyl azide and primary [T3241] N N Ph amines, however, these azide sources potentially have highly explosive character, which makes it difficult to handle. 2-Azido- Ph 1,3-dimethylimidazolinium hexafluorophosphate [A2457], which N N N was developed by Kitamura et al., is a crystalline diazotransfer reagent having high thermal stability and low explosibility. The differential scanning calorimetry (DSC) experiment of A2457 has Chiba et al. have reported a new click reaction using N-succinimidyl revealed that the exothermic decomposition temperature was 4-(azidosulfonyl)benzoate [S0973] and N-(1-Thioxoethyl)glycine approximately 200 °C. Moreover, A2457 has tested negative for [T3312]. 24) This reaction needs no metal ion species, and the the impact and friction-sensitivity tests.19) sulfonyl azide group of S0973 and thioamide group of T3312 Under basic conditions, A2457 reacts with several kinds of primary reacts to form the sulfoamidine moiety. Furthermore, the reaction amines in a short time to afford the corresponding diazo proceeds at room temperature in water and is applicable to the compounds in high yields.20) In these reactions, the by-products biorthogonal click reaction. can be removed by conventional extraction procedures due to their high solubility in water. O O S N CH3 OH O N PF6 CH3 N N O H N3 3 O DMAP S N + RNH2 R N3 O O CH Cl CH3 2 2 [S0973] [T3312] [A2457] 1 2 Entry R A2457(eq.) DMAP(eq.) Temp. Time(h) Yield(%) R NH2 + S0973 R NH2 + T3312 1Ph1.1581.1 rt 2.5 7 24-MeC H 1.15 1.1 rt 1.5 94 O O 6 4 S CH3 50°C N H 314-AcC6H4 .1583 5 3 3 N H 2 N S N R 4 4-O2NC6H4 2 3 50°C 4 61 R1 H O O 51-naphthyl 1.3 1.1 50°C 1.5 92 a) 61PhCH2CH2 .15 5 rt 0.25 74 711-adamantyl .15 1.1 rt 0.33 71 H2OorEtOH a) Et3NisusedinsteadofDMAP.
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