Table 1.

Initial optimization of on-DNA [3+2] nitrone–olefin cycloaddition

entry	time (h)	temp (°C)	MeNHOH (equiv)	buffer	buffer volsg	2 (%)h
1	12	70	25	Na2HPO4a	2	70
2	12	90	25	Na2HPO4a	2	88
3	12	100	25	Na2HPO4a	2	84f
4	12	70	25	pyrrolidineb	0.1	54
5	12	90	100	Na2HPO4a	2	64
6	4	90	25	Na2HPO4a	0.5	86
7	4	90	25	NaH2PO4c	0.1	93
8	12	90	25	NaH2PO4c	0.5	81f
9	4	90	25	NaH2PO4d	2	90
10	4	90	25	NaH2PO4d	8	71
11	4	90	25	NaOAce	2	91
12	4	90	25	NaOAce	8	>98

^a1.0 M aq buffer (pH 9.2).

^b0.2 M DMA solution.

^c1.0 M aq buffer (pH 4.2).

^d0.1 M aq buffer (pH 5.9).

^e0.1 M aq buffer (pH 5.0).

^fSignificant DNA damage observed.

^gCompared to amount of 1 stock solution (0.8 mM) added.

^hDetermined by UPLC-MS.