Dbco acid

Example 10

Amines on PEG₈-Amine (prepared as previously described) were partially reacted with a cyclooctyne-containing molecule to form PEG₈-Cyclooctyne/Amine. PEG₈-Amine was dissolved in DCM, and 0.5 equivalents of diisopropylcarbodiimide (DIPCDI) were added to a separate flask with DCM while on ice and under nitrogen flow and constant stirring. Next, 0.5 equivalents of hydroxybenzotriazole (HOBt) and 0.5 equivalents of aza-dibenzocyclooctyne with a pendant carboxylic acid (DBCO-acid; Click Chemistry Tools) were added to the mixture and allowed to stir for 10 min. While waiting, one equivalent of N,N-diisopropylethylamine (DIPEA) was added to the dissolved PEG₈-Amine. Finally, this mixture was slowly added to the activated DBCO, and the reaction was allowed to proceed for 24 h on an ice bath under constant stirring and nitrogen gas. Following that process, the urea precipitate was filtered out, and rotovapping, diethyl ether precipitation, and drying were performed. The product was then dissolved in distilled H₂O and underwent the same extraction procedure that was done for the PEG₈-Amine. Further rotovapping, diethyl ether precipitation, and drying were done. 1H NMR (300 MHz, CDCl₃, δ): (s, 902.55H, PEG), 5.1 (d, 2H, —CH₂—). NMR of the product confirmed the conversion of 50% of amines to cyclooctynes (PEG₈-Cyclooctyne/Amine) via the presence of a doublet at 5.1 ppm.

Example 10

Amines on PEG₈-Amine (prepared as previously described) were partially reacted with a cyclooctyne-containing molecule to form PEG₈-Cyclooctyne/Amine.

PEG₈-Amine was dissolved in DCM, and 0.5 equivalents of diisopropylcarbodiimide (DIPCDI) were added to a separate flask with DCM while on ice and under nitrogen flow and constant stirring. Next, 0.5 equivalents of hydroxybenzotriazole (HOBt) and 0.5 equivalents of aza-dibenzocyclooctyne with a pendant carboxylic acid (DBCO-acid; Click Chemistry Tools) were added to the mixture and allowed to stir for 10 min. While waiting, one equivalent of N,N-diisopropylethylamine (DIPEA) was added to the dissolved PEG₈-Amine. Finally, this mixture was slowly added to the activated DBCO, and the reaction was allowed to proceed for 24 h on an ice bath under constant stirring and nitrogen gas. Following that process, the urea precipitate was filtered out, and rotovapping, diethyl ether precipitation, and drying were performed. The product was then dissolved in distilled H₂O and underwent the same extraction procedure that was done for the PEG₈-Amine. Further rotovapping, diethyl ether precipitation, and drying were done. 1H NMR (300 MHz, CDCl₃, δ): (s, 902.55H, PEG), 5.1 (d, 2H, —CH₂—). NMR of the product confirmed the conversion of 50% of amines to cyclooctynes (PEG₈-Cyclooctyne/Amine) via the presence of a doublet at 5.1 ppm.