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. Author manuscript; available in PMC: 2019 Apr 26.
Published in final edited form as: Angew Chem Int Ed Engl. 2016 Dec 8;56(1):243–247. doi: 10.1002/anie.201609607

Figure 4.

Figure 4

a) N-Ac CBI double prodrug 5 reaction with tetrazine 2c leads to the formation of intermediate 6 that undergoes a Winstein spirocyclization to afford the bioactive cyclopropanyl 7. b) General protocol for tetrazine 2c-mediated intracellular decaging of 5. c) HPLC time-course of the reaction between 5 and 2c. d) Cytotoxicity fitted dose-response curves of tetrazine 2c, double prodrug 5 and drug 7 in A549 cells, obtained after 46 hours 30 min of exposure. e) Half maximal Inhibitory concentration (IC50) of tetrazine 2c, double prodrug 5 and drug 7, in A549 and HepG2 cells. f) Cytotoxic effects of intracellular activation of the prodrug 5 by tetrazine 2c inside A549 cells. For data on HepG2 cells, see the SI.