反应详情

N-hydroxysuccinimide trifluoroacetate was prepared by stirring N-hydroxysuccinimide (NHS) and 4 eq trifluoroacetic anhydride for 5 h. The mixture was concentrated under reduced pressure and further dried under high vacuum overnight. The product was obtained as a white, highly hygroscopic solid and stored in an anhydrous desiccator before use. The obtained approximately 1.1 g 2,2′-(hex-5-ynylazanediyl)diacetic acid was activated by 2.4 eq N-hydroxysuccinicimide trifluoroacetate in 10 mL anhydrous DMF under a stream of dry N2. The mixture was stirred overnight and monitored by TLC using hexanes:ethyl acetate (=2:1) as the mobile phase. After completion of the reaction, the mixture was concentrated to approximately 500 μL by rotary evaporation and subjected to flash chromatography using hexanes:ethyl acetate (=2:1) as the mobile phase. The final product, NHS-activated 2,2′-(hex-5-ynylazanediyl)diacetic acid (CXL-1) was concentrated by rotary evaporation, and obtained as a pale yellow oil. Several 200 μL aliquots of 50 mM stock solution dissolved in anhydrous dimethyl sulfoxide (DMSO) were prepared and stored at −80° C. The sealed stock aliquots were opened immediately before use, and NHS activation was verified by ESI-MS in 100% ACN. ESI-MS [M+H]+ m/z 408.1, [M+Na]+ m/z 420.0. This reaction yield can be improved by adding stoichiometric equivalents of triethylamine.

1. concentrationThe mixture was concentrated under reduced pressure
2. customfurther dried under high vacuum overnight
3. customThe product was obtained as a white, highly hygroscopic solid
4. customstored in an anhydrous desiccator before use
5. customAfter completion of the reaction
6. concentrationthe mixture was concentrated to approximately 500 μL by rotary evaporation
7. concentrationThe final product, NHS-activated 2,2′-(hex-5-ynylazanediyl)diacetic acid (CXL-1) was concentrated by rotary evaporation
8. customobtained as a pale yellow oil
9. customwere prepared
10. customstored at −80° C
11. customThis reaction yield can