2,4-Dinitrobenzamide-5-mustards as Prodrugs
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 6 1209
30.31 (CH2Br). MS M+ calcd for C15H18Br2N4O7, 527.9501,
525.9522, 523.9542; found, 527.9502, 525.9535, 523.9545.
3-(5-(Bis(2-bromoethyl)amino)-2,4-dinitrobenzamido)pro-
panoic Acid (30). A solution of 28 (4.00 g, 7.58 mmol) and 1 N
NaOH (20 mL, 20 mmol) in 1:1 THF/MeOH (80 mL) was stirred
at room temperature for 2 h. After acidification with 3 N HBr, the
solution was concentrated to a small volume and extracted with
EtOAc. Workup gave 30 (3.11 g, 80%): mp (Me2CO/water)
8.68 (t, J ) 3.3 Hz, 1H), 8.53 (s, 1H), 7.46 (s, 1H), 4.82 (d, J )
5.0 Hz, 1H), 4.56 (t, J ) 5.7 Hz, 1H), 4.33 (t, J ) 5.1 Hz, 2H),
3.83 (t, J ) 6.1 Hz, 2H), 3.73 (t, J ) 5.1 Hz, 2H), 3.64 (m, 3H),
3.44-3.38 (m, 4H), 3.13 (s, 3H); 13C NMR δ 164.51, 147.08,
138.03, 137.30, 136.45, 124.20, 121.38, 70.01, 66.74, 63.68, 52.92,
49.68, 42.70, 41.54, 36.56. Anal. (C15H21ClN4O10S) C, H, N.
Further elution with EtOAc/MeOH (from 50:1 to 10:1) gave 35
(2.38 g, 71%) as a yellow oil: 1H NMR [(CD3)2SO] δ 8.66 (t, J )
5.8 Hz, 1H, CONH), 8.54 (s, 1H, H-3), 7.48 (s, 1H, H-6), 4.81 (d,
J ) 5.0 Hz, 1H, CHOH), 4.59 (t, J ) 5.1 Hz, 1H, CH2OH), 4.35
(m, 4H, 2× CH2OMs), 3.66 (m, 4H), 3.62 (m, 1H), 3.46 - 3.36
(m, 4H), 3.13 (s, 6H); 13C NMR δ 164.48, 147.09, 138.26, 137.27,
136.60, 124.17, 121.72, 70.02, 66.69 (2), 63.68, 50.21 (2), 42.68,
36.55 (2). HRMS (FAB, m/z) calcd for C16H25N4O13S2, 545.0860
(MH+); found, 545.0856.
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166 °C; H NMR [(CD3)2SO] δ 12.29 (br, 1H), 8.79 (t, J ) 5.6
Hz, 1H), 8.54 (s, 1H), 7.40 (s, 1H), 3.73, 3.68 (2× br t, J ) 5.1
Hz, 8H), 3.43 (dt, J ) 6.9 Hz, 2H), 2.53 (t, J ) 6.9, 5.6 Hz, 2H);
13C NMR δ 172.70 (CO2H), 164.43 (CONH), 146.67 (s), 137.86
(s), 137.18 (s), 136.16 (s), 124.31 (d), 120.84 (d), 52.36 (CH2N),
35.16 (CH2CONH), 33.13 (CH2CO2CH3), 30.33 (CH2Br). Anal.
(C14H16Br2N4O7‚0.5Me2CO) C, H.
N-(2-Hydroxyethyl)-5-[bis(2-bromoethyl)amino]-2,4-dinitroben-
zamide (25) and 2-((2-Bromoethyl)-5-{[(2-hydroxyethyl)amino]-
carbonyl}-2,4-dinitroanilino)ethyl Methanesulfonate (41; Scheme
3). A solution of the acid chloride of 52 (3.20 g, 6.79 mmol) in
dry Me2CO (80 mL) was treated at 0 °C with 2-aminoethanol (1.24
g, 20.3 mmol). After stirring at 0 °C for 5 min, the mixture was
acidified to pH 2-3 with 0.2 N HBr, concentrated to half volume,
and then solid NaBr was added. The mixture was extracted with
EtOAc (2×), and the combined extracts were washed with saturated
NaBr solution, dried (Na2SO4), and evaporated. The residue was
chromatographed on silica gel, eluting with EtOAc/MeOH (15:1),
to give 2-(5-{[(2-hydroxyethyl)amino]carbonyl}{2-[(methylsulfo-
nyl)oxy]ethyl}-2,4-dinitroanilino)ethyl methanesulfonate (60; 2.87
g, 82%) as a gum that was used directly.
A mixture of 60 (1.80 g, 3.50 mmol) and LiBr (0.43 g, 4.95
mmol) in DMF (5 mL) was stirred at 60 °C for 2 h. The reaction
was then poured into a saturated NaBr solution and extracted with
EtOAc (2×). The combined extracts were washed with saturated
NaBr solution, dried (Na2SO4), and concentrated under reduced
pressure. The residue was chromatographed on silica gel, eluting
with EtOAc, to give 25 (0.78 g, 46%).
2-((2-Bromoethyl)-5-{[(2,3-dihydroxypropyl)amino]carbonyl}-
2,4-dinitroanilino)ethyl Methanesulfonate (42). A solution of 35
(1.28 g, 2.53 mmol) in EtOAc (100 mL) was treated with LiBr
(347 mg, 4.0 mmol) at 60 °C for 2 h. Volatiles were removed under
reduced pressure, and the residue was adsorbed directly onto silica
gel and chromatographed. Elution with EtOAc gave 5-[bis(2-
bromoethyl)amino]-N-(2,3-dihydroxypropyl)-2,4-dinitrobenza-
mide (27; 0.4 g 31%). Further elution with EtOAc/MeOH (from
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1:0 to 5:1) gave 42 (0.62 g, 46%): mp (EtOAc) 117-118 °C; H
NMR [(CD3)2SO] δ 8.68 (t, J ) 5.8 Hz, 1H), 8.53 (s, 1H), 7.46 (s,
1H), 4.82 (d, J ) 5.0 Hz, 1H), 4.56 (t, J ) 5.1 Hz, 1H), 4.32 (m,
2H), 3.75-3.60 (m, 7H), 3.46-3.36 (m, 4H), 3.13 (s, 3H); 13C
NMR δ 164.48, 146.84, 138.05, 137.29, 136.52, 124.18, 121.40,
70.01, 66.74, 63.68, 52.89, 49.56, 42.69, 36.55, 30.20. Anal.
(C15H21BrN4O10S) C, H, N, Br.
5-[(2-Bromoethyl)(2-chloroethyl)amino]-2,4-dinitrobenza-
mide (38; Scheme 4). A mixture of 5-[(2-chloroethyl)[2-(methyl-
sulfonyloxy)ethyl]amino]-2,4-dinitrobenzamide16 (36; 0.91 g, 2.2
mmol) and LiBr (0.21 g, 2.4 mmol) in anhydrous MeCN (25 mL)
was stirred under reflux for 1.5 h and then concentrated under
reduced pressure. The residue was chromatographed on silica gel,
eluting with CH2Cl2/EtOAc (3:2) to give a crude product contami-
nated with the dibromomustard 23. Purification by multiple
recrystallization from EtOAc/i-Pr2O gave 38 (595 mg, 68%): mp
Further elution with EtOAc/MeOH (9:1) gave 41 (0.73 g,
42%): mp (EtOAc) 102-104 °C; 1H NMR [(CD3)2SO] δ 8.70 (t,
J ) 5.7 Hz, 1H), 8.54 (s, 1H), 7.46 (s, 1H, H-6), 4.76 (J ) 5.5 Hz,
1H), 4.34 (t, J ) 5.1 Hz, 2H), 3.74 (t, J ) 5.1 Hz, 2H), 3.70 (br s,
4H), 3.53 (q, J ) 6.0 Hz, 2H), 3.31 (q, partially obscured, J ) 6.1
Hz, 2H), 3.14 (s, 3H). Anal. (C14H19BrN4O9S‚0.25EtOAc; detected
by NMR) C, H, N.
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153 °C; H NMR [(CD3)2SO] δ 8.52 (s, 1H), 8.17-7.82 (2 × s,
2H), 7.43 (s, 1H, H-6), 3.82 (t, J ) 5.8 Hz, 2H), 3.77-3.63 (m,
6H). Anal. (C11H12BrClN4O5) C, H, N, Cl.
5-[(2-Bromoethyl)[2-(methylsulfonyloxy)ethyl]amino]-2,4-
dinitrobenzamide (39). A mixture of 5-[bis-[2-(methylsulfonyl-
oxy)ethyl]amino]-2,4-dinitrobenzamide16 (34; 1.60 g, 3.4 mmol)
and LiBr (356 mg, 4.1 mmol) in anhydrous MeCN (30 mL) was
stirred under reflux for 1 h. The mixture was concentrated under
reduced pressure, and the residue was chromatographed on silica
gel. Elution with EtOAc/CH2Cl2 (11:9) gave the dibromomustard
23, while further elution with EtOAc/CH2Cl2 (3:1) gave 39 (0.61
5-[Bis(2-iodoethyl)amino]-N-(2-hydroxyethyl)-2, 4-dinitroben-
zamide (32). A stirred mixture of 60 (1.42 g, 2.76 mmol) and NaI
(3.3 g, 22 mmol) in dry MeCN (45 mL) was heated at reflux for 1
h and then concentrated under reduced pressure. The residue was
partitioned between EtOAc and water, and the organic layer was
washed with water and evaporated. The residue was chromato-
graphed on silic gel, eluting with CH2Cl2/EtOAc (1:4), followed
by recrystallization from MeOH/EtOAc/i-Pr2O to give 32 (2.9 g,
1
g, 39%): mp (EtOAc/i-Pr2O) 160-161 °C; H NMR [(CD3)2SO]
1
δ 8.53 (s, 1H, H-3), 8.14, 7.83 (2 × s, 2H), 7.46 (s, 1H, H-6), 4.33
(t, J ) 5.1 Hz, 2H), 3.74 (t, J ) 5.1 Hz, 2H, NCH2), 3.70 (br s,
4H), 3.14 (s, 3H). Anal. (C12H15BrN4O8S) C, H, N, Br.
81%): mp 142-143 °C; H NMR [(CD3)2SO] δ 8.73 (t, J ) 5.7
Hz, 1H), 8.53 (s, 1H), 7.38 (s, 1H), 4.76 (t, J ) 5.5 Hz, 1H), 3.68
(t, J ) 6.9 Hz, 4H), 3.57-3.49 (m, 2H), 3.39 (t, J ) 6.9 Hz, 4H),
3.34-3.26 (m, partially obscured, 2H). Anal. (C13H16I2N4O6) C,
H, N, I.
5-[N-(2-Iodoethyl)-N-[2-(methylsulfonyloxy)ethyl]amino]-2,4-
dinitrobenzamide (43). A mixture of 34 (1.12 g, 2.38 mmol) and
NaI (0.46 g, 3.07 mmol) in anhydrous MeCN (20 mL) was stirred
at reflux for 1 h. The mixture was concentrated under reduced
pressure, and the residue was chromatographed on silica gel. Elution
with EtOAc/CH2Cl2 (1:1) gave the diiodomustard, while further
elution with EtOAc/CH2Cl2 (3:1) gave 43 (0.49 g, 41%): mp (Me2-
2-(5-{[(2,3-Dihydroxypropyl)amino]carbonyl}{2-[(methylsul-
fonyl)oxy]ethyl}-2,4-dinitroanilino)ethyl Methanesulfonate (35)
and 2-((2-Chloroethyl)-5-{[(2,3-dihydroxypropyl)amino]carbo-
nyl}-2,4-dinitroanilino)ethyl Methanesulfonate (37). The acid
chloride of 52 (2.9 g, 6.18 mmol; containing some of the
corresponding chloromesylate) was treated with 3-amino-1,2-
propanediol for 10 min, then acidified to pH 2-3 with 1 N HCl.
Most of the solvent was evaporated, and the residue was partitioned
between water and EtOAc. The aqueous layer was extracted with
EtOAc (2 × 80 mL), and the combined organic phases were dried
and evaporated under reduced pressure. The residue was adsorbed
directly onto silica gel and chromatographed. Elution with EtOAc
gave 2-((2-chloroethyl)-5-{[(2,3-dihydroxypropyl)amino]carbonyl}-
2,4-dinitroanilino)ethyl methanesulfonate 37 (0.5 g, 17%) as a
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CO/EtOAc/i-Pr2O) 160 °C; H NMR [(CD3)2SO] δ 8.52 (s, 1H,
H-3), 8.14-7.83 (2 × s, 2H), 7.44 (s, 1H, H-6), 4.33 (t, J ) 5.1
Hz, 2H), 3.73 (t, J ) 5.1 Hz, 2H), 3.65 (t, J ) 6.9 Hz, 2H, 3.40 (t,
J ) 6.9 Hz, 2H), 3.13 (s, 3H). Anal. (C12H15IN4O8S) H, N, I, C:
found 29.4; calculated 28.7%.
2,2′-(5-Carbamoyl-2,4-dinitrophenylazanediyl)bis(ethane-2,1-
diyl) Disulfamate (44). A solution of 5-[bis(2-hydroxyethyl)amino]-
2,4-dinitrobenzamide16 (61; 300 mg, 0.95 mmol) in DMA (3 mL)
was treated at -5 °C with sulfamoyl chloride (441 mg, 3.82 mmol).
The mixture was stirred at 0 °C for 15 min and at room temperature
1
yellow solid: mp 118-121 °C (EtOAc); H NMR [(CD3)2SO] δ