Click Chemistry

N-(Azide-PEG8)-N'-Boc-Lys is a PEG linker featuring an azide group, and a lysine featuring a Boc-protected ε-amine and a free carboxylic acid. The azide is easily used in click chemistry to form stable triazoles with terminal alkynes and cyclooctynes while the carboxylic acid may be used to couple with amines or alcohols to form amides or esters respectively. Finally, the ε-amine may be Boc-deprotected with acid to allow for use such as in couplings with carboxylic acids, reductive aminations with aldehydes or ketones, SNAr with electron-deficient aromatic groups, or for constructing N-heterocycles such as pyrroles.

N-(Azide-PEG8)-N'-Boc-Lys(4-aminophenyl)methanol is a PEG linker featuring an azide, a hydrophilic PEG spacer, and a lysine that is Boc-protected at its ε-amine and features a PAB group ligated on its carboxylic acid. The azide is easily used in click chemistry to form stable triazoles with terminal alkynes and cyclooctynes while the benzylic alcohol on the PAB is free to react with electrophiles such as carboxylic acids to form esters with a target compound. Finally, the Boc-protecting group may be removed with acid to reveal a primary amine that may be used in a variety of ways such as in coupling, reductive aminations, SNAr, or for constructing N-heterocycles such as pyrroles.

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t-Boc-N-amido-PEG4-Val-Cit is a protease-cleavable ADC linker featuring a Boc-protected amine, a hydrophilic PEG spacer, and a Val-Cit dipeptide. The Val-Cit dipeptide is cleavable by cell proteases and features a carboxylic acid which is free for coupling reactions with amines to form amides. The Boc can be removed under acidic conditions to reveal a free primary amine, which may be used in a variety of reactions such as coupling or reductive amination.

Methyltetrazine-activated Cy7 probe that reacts with TCO-containing compounds via an Inverse-Electron-Demand Diels-Alder reaction to form a stable covalent bond and does not require Cu-catalyst or elevated temperatures. The inverse-electron demand Diels-Alder cycloaddition reaction of TCO with tetrazines is a bioorthogonal reaction that possesses exceptional kinetics (k > 800 M-1 s -1) and selectivity. Such excellent reaction rate constants are unparalleled by any other bioorthogonal reaction pair described to date.