Table 3.

Second-order reaction rate constant between unstrained olefin dienophiles with Fluorescein-Tetrazine

Entry	Unstrained Olefin	k (10−3 M−2 s−1)
1	prop-2-en-1-ol	9.4 ± 1.2
2	(E)-but-2-en-1-ol	1.9 ± 0.1
3	but-3-en-1-ol	26 ± 5
4	pent-4-en-1-ol	36 ± 4
5	2-(vinyloxy) ethan-1-ol	81 ± 1
6	(R)-N-(5-aminohexyl) acrylamide	1.2 ± 0.1
7	(R)-N-(5-aminohexyl) but-3-enamide	1.7 ± 0.2
8	(R)-N-(5-aminohexyl) pent-4-enamide	11 ± 2
9	(R)-N-(5-aminohexyl) hex-5-enamide	16 ± 1
10	(R,E)-N-(5-aminohexyl)-3-methoxyacrylamide	19 ± 1

Fluorescein-Tetrazine = N-(2-(3-(3′,6′-dihydroxy-3-oxo-3H-spiro[isobenzofuran-1,9′-xanthen]-5-yl) thioureido) ethyl)-4-(1,2,4,5-tetrazin-3-yl) benzamide