The N3C4 bond with the 5thymine ruptures.12 We hence conclude that the new solution observed in the chromatogram shown in Figure 2A is probably a water adduct possessing the structure shown for 1 (Scheme 1). SP Therapy in 18O Water. To confirm that 1 is definitely an adduct with water, the reactions described above were performed in 18O labeled water containing 0.2 M KOH for 48 h. Subsequent ESIMS analyses indicated that 18O was indeed incorporated into 1. Even so, to our surprise, the incorporation of two 18O atoms was observed. Evaluation of unreacted SP TpT remaining in these reaction mixtures revealed a mass of unlabeled SP 2 amu, suggesting that intact SPs exchange one 18O atom also,13 which most likely resultsdx.doi.org/10.1021/ja505407p | J. Am. Chem. Soc. 2014, 136, 12938Journal of the American Chemical Society SchemeArticleFigure three. ESIMS spectra (unfavorable ion mode) with the SP hydrolysis reaction in 0.two M KOH at ambient temperature in 97 18O water. (A) The gradual incorporation of 18O into SP. The peaks indicated by blue arrows exhibit an m/z of 545.1, corresponding towards the [M H] signal of SP with out any 18O incorporation. The peaks indicated by red arrows exhibit an m/z of 547.1, corresponding for the [M H] signal of SP with 1 18 O incorporated. (B) The gradual incorporation of 18O into the SP hydrolysis solution 1. The peaks indicated by blue arrows exhibit an m/z of 563.1, corresponding to the [M H] signal of 1 without having any 18O incorporation. The peaks indicated by orange arrows exhibit an m/z of 565.1, which correspond towards the [M H] signal of 1 with one 18O incorporated and steadily decrease in the course of the course from the reaction.Buy1780637-40-2 The peaks indicated by green arrows exhibit an m/z of 567.Formula of 5-Nitro-3-pyridinol 1, which correspond towards the [M H] signal of 1 with two 18O incorporated. (C) Time course indicating the incorporation of 18O into SP and SP hydrolysis product 1. The incorporation of the second 18O into 1 is slower than the 18O incorporation into SP, suggesting that the second 18O incorporation occurs by reacting using the 18O labeled SP.from an oxygen exchange involving the C4O on the saturated 5thymine of SP and water. To understand the oxygen exchange method noted above, the hydrolysis of SP in 18O water/0.two M KOH was reexamined by ESIMS. As shown in Figure 3, a linear incorporation of 18O into SP was observed inside the very first 1.5 h (the rate of 18O incorporation is reported in Table 1). Just after four h the reaction rate slowed considerably and reached completion just after two days, as indicated by the fact that 96 of the SP present contained a single 18 O atom, equal for the 18O abundance in the 18O water employed.PMID:25429455 In comparison, analysis of 1 revealed that within the very first 30 min 92 of 1 contained a single 18O label; the double18O labeled 1 became obvious right after 1 h from the reaction and reached completion in 2 days (Figure 3C). These outcomes clearly indicate that the oxygen at the C4O moietyTable 1. Prices of Formation of 1 and 18O Incorporation into SP TpTreaction pH 13.9 13.three 12 10.5 eight.7 7.aformation of 1 (M/h)a 427.three 20.0 118.four 7.1 8.3 0.O incorporation into SP TpT (M/h)b 107.0 five.8 79.1 three.five 4.0 0.25 1.05 0.09 0.14 0.HPLC evaluation. bESIMS evaluation.exchanged with water and, additional, that a tetrahedral hemiaminal intermediate should exist (Scheme 2) which can eitherdx.doi.org/10.1021/ja505407p | J. Am. Chem. Soc. 2014, 136, 12938Journal in the American Chemical Society SchemeArticleFigure four. (A) HPLC chromatograph (260 nm) in the decomposition reaction of 1 at 90 for 30,.
