(S)-N-((3R,4S,5S)-1-((S)-2-((1R,2R)-3-(((S)-1-(4-aminophenyl)-3-azidopropan-2-yl)amino)-1-methoxy-2-methyl-3-oxopropyl)pyrrolidin-1-yl)-3-methoxy-5-methyl-1-oxoheptan-4-yl)-2-((S)-2-(dimethylamino)-3-methylbutanamido)-N,3-dimethylbutanamide

Duostatin 5 is a cytotoxin designed based on dolastatin, can meet the requirement of serving as an effective cytotoxin in ADC, but has the advantages of fewer synthesis steps, easy operation, less difficulty in quality control and more stable chemical synthesis process[1]. Duostatin 5 is a click chemistry reagent, it contains an Azide group and can undergo copper-catalyzed azide-alkyne cycloaddition reaction (CuAAc) with molecules containing Alkyne groups. It can also undergo strain-promoted alkyne-azide cycloaddition (SPAAC) reactions with molecules containing DBCO or BCN groups.

[1] Toxin for antibody drug conjugate and preparation method thereof. CN107857798B.