Int. J. Mol. Sci. 2021, 22, 5073
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target compound as a fine yellow powder (1.40 g, 80%). H NMR (400 MHz, DMSO-d6):
δ
10.14 (s, 1H), 7.43–7.45 (d, J = 2.4, 1H), 6.54–6.56 (m, 1H), 6.41 (s, 1H), 7.14–7.19 (m, 1H),
6.48 (s, 1H), 4.34 (s, 2H).
4-(Chloromethyl)-7-((((2R,3S,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-
2-yl)methyl)amino)-2H-chromen-2-one acetic acid salt (12) [35]: 2,5-anhydro-2-carbaldehyde-
D-mannitol (800 mg, 4.8 mmol) and compound 11 (500 mg, 2.40 mmol) were dissolved
in methanol (40 mL). AcOH (4.0 mL) was added to adjust the pH to <6, and the mixture
was stirred at room temperature for 10–15 min, followed by portion-wise addition of
NaBH3CN (4 x 120 mg, 1.92 mmol, every 30–40 min). The reaction mixture was stirred
at room temperature for overall 24 h. The mixture was concentrated to dryness under
reduced pressure, absorbed on silica gel, and purified by column chromatography on silica
gel eluting with 0%
acid salt, yellow foam in 90% yield (840 mg): H NMR (400 MHz, CD3OD):
−
10% methanol in CH2Cl2. The product was obtained as an acetic
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δ 7.45–7.47 (d,
J = 9.2, 1H), 6.6–6.68 (dd, J1 = 2.4, J2 = 8.8, 1H), 6.48 (d, J = 2.4, 1H), 6.13–6.15 (d, J = 2.4, 1H),
5.45 (s, 1H), 4.71 (m, 2H), 3.93–3.96 (m, 2H), 3.87–3.88 (m, 1H), 3.60–3.69 (m, 2H), 3.50 (s,
1H), 3.29 (m, 2H). MS (M + H+): 356.1
(7-((((2R,3S,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)methyl)-am-
ino)-2-oxo-2H-chromen-4-yl)methyl 4-(4-(bis(2-chloroethyl)amino)phenyl)butanoate (III,
ManCou–Ester–CLB): to the solution of 12 (234 mg, 0.66 mmol) in dry DMF (5 mL) under
argon, chlorambucil (200 mg, 0.66 mmol) and DMAP (80 mg, 0.66 mmol) was added, and
the mixture was stirred at room temperature for 24 h. The mixture was concentrated and
purified by column chromatography, using methanol/CH2Cl2 up to 30% to yield III as a
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light-yellow syrup. H NMR (400 MHz, CD3OD):
δ 7.37–7.39 (d, J = 9.2, 1H), 6.95–7.05 (m,
2H), 6.60–6.70 (m, 2H), 6.55 (d, J = 4, 1H), 6.05 (m, 2H), 5.22 (s, 2H), 4.90 (m, 4H), 4.61 (m,
1H), 3.93–3.96 (m, 1H), 3.69 (s, 1H), 3.61–3.63 (m, 8H), 3.54–3.56 (m, 2H), 3.29–3.32 (m, 2H),
2.40–2.44 (dd, 2H), 2.50–2.54 (dd, 2H), 1.81 (m, 2H). HRMS (ESI): m/z [M + H]+ calc’d for
C30H36Cl2N2O8: 622.18487; found: 622.18446.
Prop-2-yn-1-yl 4-(4-(bis(2-chloroethyl)amino)phenyl) butanoate (13) [36]: Prop-2-yn-
1-ol (55 mg, 0.985 mmol) was dissolved in DCM (10 mL) and cooled in an ice bath. Chlo-
rambucil (200 mg, 0.657 mmol), DMAP (10 mg, 0.065 mmol), and DCC (1 mL, 0.985 mmol)
were added to the cold solution, the mixture was purged with argon and stirred in a closed
system for 24 h at room temperature. The final mixture was concentrated and purified
by column chromatography on silica gel, using EtOAc/Hex up to 10% to extract the title
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product in 100% yield (228 mg). H NMR (400 MHz, CDCl3):
δ 7.06–7.08 (d, J = 8, 2H),
6.63–6.65 (d, J = 8, 2H), 4.67 (s, 2H), 3.68–3.72(m, 4H), 3.61–3.64 (m, 4H), 2.55–2.59 (t, J = 8,
2H), 2.35–2.39 (t, J = 8, 2H), 2.47 (t, J = 4, 1H), 1.91–1.95 (p, J = 8, 2H). MS (M + H+): 342.1.
4-(Azidomethyl)-7-((((2R,3S,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-
2-yl)methyl)amino)-2H-chromen-2-one (14) [22]: To the solution of 12 (2.3 g, 11.0 mmol) in
dry DMF (30 mL) under argon, NaN3 (2.85 g, 43.8 mmol) was added, and the mixture was
stirred at room temperature for 4 h. The mixture was diluted with EtOAc (400 mL), washed
with brine (4
residue was absorbed on silica gel and purified by column chromatography on silica gel,
eluting with 0 10% methanol in CH2Cl2. The resulting solid was suspended in CH2Cl2,
×
100 mL), and dried with MgSO4. After filtration and concentration, the
−
followed by addition of hexanes and filtered, washing with hexanes, to provide the title
compound as a dark yellow solid in 78% yield (1.86 g). Prolonging the reaction time was
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found to be detrimental for yields. H NMR (400 MHz, DMSO-d6): δ, 7.37–7.35 (d, J = 8.4,
1H), 6.58–6.55 (dd, J1 = 2.0, J2 = 8.8, 1H), 6.43 (d, J = 2.0, 1H), 6.23 (bs, 2H), 6.05 (s, 1H),
4.69 (s, 2H) ppm. HRMS (ESI): m/z [M + H]+ calc’d for C10H9N4O2: 217.07257; found:
217.07222.
(1-((7-((((2R,3S,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)methyl)-
amino)-2-oxo-2H-chromen-4-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl4-(4-(bis(2-chloroethyl)-
amino)phenyl)butanoate (IV, Man–Click–CLB) [28]: The salt 14 (105 mg, 0.249 mmol) was
dissolved in acetonitrile/water 1:1 mixture (v/v, up to 4 mL) and the solution was purged
with argon for few minutes. Propargyl ester (13) (114 mg, 0.274 mmol) was added, fol-