[N+:1]([C:4]1[CH:5]=[C:6]2[N:12]([CH:13]3[CH2:18][CH2:17][CH2:16][CH2:15][O:14]3)[N:11]=[CH:10][C:7]2=[N:8][CH:9]=1)([O-])=O.[N+](C1C=C2NN=CC2=NC=1)([O-])=O.O1C=CCCC1.CS(O)(=O)=O.C(=O)(O)[O-].[Na+]>O1CCCC1>[O:14]1[CH2:15][CH2:16][CH2:17][CH2:18][CH:13]1[N:12]1[C:6]2[C:7](=[N:8][CH:9]=[C:4]([NH2:1])[CH:5]=2)[CH:10]=[N:11]16-Nitro-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[4,3-b]pyridine. A solution of 6-nitro-1H-pyrazolo[4,3-b]pyridine (2 g, 12.19 mmol), 3,4-dihydro-2H-pyran (1.538 g, 18.28 mmol) and methanesulfonic acid (0.119 mL, 1.828 mmol) in tetrahydrofuran (100 mL) was heated to 70° C. overnight. The reaction was cooled and neutralized with aqueous sodium bicarbonate to pH 7, and then extracted with ethyl acetate. The combined organics were dried over magnesium sulfate, filtered, concentrated on a rotary evaporator. Flash chromatography (eluting with 0-50% ethyl acetate in hexane) gave the desired product as an off white solid (1.3 g, 5.24 mmol, 43.0% yield). (ESI) m/z 249.3 [M+1]+.
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