Copper-Free Click Chemistry

Cu-free cycloadditions offer efficient ligation reactions useful for a variety of bioconjugation applications. When working with live cells these reactions offer the advantage of not having the cytotoxicity associated with Cu-catalyzed cycloadditions. Sigma-Aldrich now offers a suite of cyclooctynes, tetrazines and strained-alkene reagents for use in a variety of applications.

Cyclooctynes for Cu(I)-free Cycloadditions

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797685 ADIBO-PEG4-acid 90% (HPLC) C30H36N2O8
745073 N-[(1R,8S,9s)-Bicyclo[6.1.0]non-4-yn-9-ylmethyloxycarbonyl]-1,8-diamino-3,6-dioxaoctane for Copper-free Click Chemistry C17H28N2O4
742678 (1R,8S,9s)-Bicyclo[6.1.0]non-4-yn-9-ylmethanol for Copper-free Click Chemistry C10H14O
744867 (1R,8S,9s)-Bicyclo[6.1.0]non-4-yn-9-ylmethyl N-succinimidyl carbonate for Copper-free Click Chemistry C15H17NO5
777366 DBCO-Cy3 for Copper-free Click Chemistry C62H84N6O11S3
777374 DBCO-Cy5 for Copper-free Click Chemistry C64H86N6O11S3
809705 5-DBCO-PEG4-dUTP, 10mM Aqueous Solution C42H54N5O21P3
761516 Dibenzocyclooctyne-acid storage temp.: −20°C, 95% C21H19NO3
761540 Dibenzocyclooctyne-amine for Copper-free Click Chemistry C18H16N2O
760781 Dibenzocyclooctyne-fluor 488 for Copper-free Click Chemistry C39H26N2O7
761524 Dibenzocyclooctyne-N-hydroxysuccinimidyl ester for Copper-free Click Chemistry C23H18N2O5
761532 Dibenzocyclooctyne-S-S-N-hydroxysuccinimidyl ester for Copper-free Click Chemistry C28H27N3O6S2
760668 Dibenzocyclooctyne-maleimide for Copper-free Click Chemistry C25H21N3O4
759902 Dibenzocyclooctyne-PEG4-acid for Copper-free Click Chemistry C32H40N2O8
761982 Dibenzocyclooctyne-PEG4-alcohol for Copper-free Click Chemistry C29H36N2O6
760749 Dibenzocyclooctyne-PEG4-biotin conjugate for Copper-free Click Chemistry C39H51N5O8S
760773 Dibenzocyclooctyne-PEG4-Fluor 545 for Copper-free Click Chemistry C54H57N5O10
764019 Dibenzocyclooctyne-PEG4-N-hydroxysuccinimidyl ester 95% C34H39N3O10
760676 Dibenzocyclooctyne-PEG4-maleimide for Copper-free Click Chemistry C36H42N4O9
762040 Dibenzocyclooctyne-sulfo-N-hydroxysuccinimidyl ester for Copper-free Click Chemistry C25H21N2NaO8S
760706 Sulfo-dibenzocyclooctyne-biotin conjugate for Copper-free Click Chemistry C37H50N6O7S2

Staudinger Ligation

The reaction between an azide and a phosphine forming an aza-ylide was first reported in 1919 by Nobel Prize laureate Herrmann Staudinger. It has found widespread application in chemical synthesis, and is valuable as a highly chemoselective ligation method for the preparation of bioconjugates. Both reactive functionalities involved in the Staudinger ligation reaction are bioorthogonal and readily combine at room temperature in aqueous environments. These conditions make it possible to exploit the Staudinger ligation in complex cellular and organismal environments in the investigation of various processes in chemical biology. Sigma-Aldrich is happy to provide phosphine ligands for your various Staudinger ligation and conjugation applications.

Learn More about the Staudinger Ligation
Staudinger Ligation
Copper-Free Click Chemistry: Bioorthogonal Reagents for Tagging Azides
Staudinger Ligation
Nontraceless Staudinger Ligation
Traceless Staudinger Ligation
Azide Building Blocks for Chemical Ligation

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670359 Acetylthiomethyl-diphenylphosphine borane complex ≥98.0% C15H18BOPS
290734 Dabco® 33-LV C6H12N2
578282 1,4-Diazabicyclo[2.2.2]octane hydrochloride, polymer-bound 100-200 mesh, extent of labeling: ~2.0 mmol/g N loading, 1 % cross-linked with divinylbenzene  
679011 2-(Diphenylphosphino)terephthalic acid 1-methyl 4-pentafluorophenyl diester 97% C27H16F5O4P
715069 N-Succinimidyl 3-(diphenylphosphino)propionate 95% C19H18NO4P

Tetrazine/Strained-alkene Click Chemistry Reagents

The reaction of 1,2,4,5 tetrazines with strained alkenes has been applied as a rapid bioorthogonal click chemistry reaction for biological labeling and cell detection applications among others. This reaction procedes rapidly via an inverse electron demand [4 + 2] Diels-Alder cycloaddition to yield a stable covalent linkage without the need for a catalyst and the only byproduct is dinitrogen. When using trans-cyclooctene, this reaction is orders of magnitude faster than azide-cyclooctyne based click chemistry and has therefore found use in applications where low concentrations of reactants are desired or faster kinetics are needed.

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761591 (4-(1,2,4,5-Tetrazin-3-yl)phenyl)methanamine hydrochloride 95%  
764396 (E)-Cyclooct-4-enol  
764523 (E)-Cyclooct-4-enyl 2,5-dioxo-1-pyrrolidinyl carbonate  
764701 2,5-Dioxo-1-pyrrolidinyl 5-[4-(1,2,4,5-tetrazin-3-yl)benzylamino]-5-oxopentanoate ≥90%  
764493 5-[4-(1,2,4,5-Tetrazin-3-yl)benzylamino]-5-oxopentanoic acid 97%  
776173 5-Norbornene-2-acetic acid succinimidyl ester 97%  
772828 5-Norbornene-2-endo-acetic acid  
900914 Methyltetrazine-NHS ester ≥95% New  
900894 Methyltetrazine-PEG4-NHS ester ≥95% New  
790435 TCO PEG4 succinimidyl ester  
790451 TCO-amine HCl salt  
790443 TCO-PEG3-maleimide  
900927 TCO-PNB ester ≥95% New