Table 2.

Kinetics of the reaction of 1 a with the tetrazines 2 a–c.

2 [a]	Dienophile	k 2×10−4  m −1 s−1
2 a	1 a	3.92±0.11
2 b	1 a	0.063±0.013
2 c	1 a	5.37±0.13
2 a	5‐norbornen‐2‐ol	1890±40

[a] The reactions were performed in 10 % H₂O in DMF and were followed by UV through the decay of UV absorption of the tetrazines. An excess of 150–350 fold of 1 a was used. In the case of 5‐norbornen‐2‐ol the kinetic rate was determined using the same solvent system with 2 a with a 20‐ to 100‐fold excess of 5‐norbornen‐2‐ol.