The synthetic procedures of probes were depicted in Scheme 1. All the designed compounds contain two parts that are chromophoric units and N-mustards “warhead”. Initially, the intermediates of chromophoric units 4, 5, and 6 and N-mustards “warhead” including 4-(2-(bis(2-chloroethyl)amino)ethoxy)benzaldehyde (3) were synthesized. Take the case of compound synthesis process of CXL118.
Fig.2 Scheme 1 Synthetic routes of compounds CXL118, CXL121, and CXL122. (a) 1,2-dibromoethane, K2CO3, DMF, 80 °C; (b) K2CO3, acetonitrile, 80 °C, (c) SOCl2, DCM, 30 °C, and (d) piperidine, acetonitrile, 60 °C. |
Full size|PPT slide
General process: 2-(2-Methyl-4H-chromen-4-ylidene)malononitrile (4) (208 mg, 1 mmol) and 4-(2-(bis(2-chloroethyl)amino)ethoxy)benzaldehyde (3) (289 mg, 1 mmol) were dissolved in dry acetonitrile (100 mL for 14 mmol) under argon. Piperidine (91 μL, 1 mmol) was added and the solution was stirred at 60 °C for 8 h. The red solution was concentrated and the product (CXL118, (E)-2-(2-(4-(2-(bis(2-chloroethyl)amino)ethoxy)styryl)-4H-chromen-4-ylidene)malononitrile) was purified by crystallization or column chromatography. Brick red solid; Yield 26%. 1H NMR (400 MHz, CDCl3, δppm): 8.93 (t, J = 12.4 Hz, 1H, Ar–H), 7.75 (t, J = 8.2 Hz, 1H, Ar–H), 7.58–7.56 (m, 4H, Ar–H), 7.45 (t, J = 4.2 Hz, 1H, Ar–H), 6.96 (d, J = 8.4 Hz, 2H, –CH=CH–), 6.85 (s, 1H, Ar–H), 6.69 (d, J = 8.6 Hz, 1H, Ar–H), 4.10 (t, J = 6.4 Hz, 2H, –O–CH2–CH2–), 3.56 (t, J = 6.2 Hz, 4H, N(CH2)2), 3.10–3.03 (m, 4H, –CH2Cl), 2.02 (m, 2H, –O–CH2–CH2–). 13C NMR (101 MHz, DMSO, δppm): 159.08, 153.37, 152.50, 139.13, 135.81, 130.56, 126.57, 125.10, 119.49, 117.56, 116.43, 115.60, 106.54, 60.00, 56.58, 53.03. MS m/z (ESI): calcd for C26H24Cl2N3O2+: 480.12; found 480.13.
(E)-2-(4-(2-(Bis(2-chloroethyl)amino)ethoxy)styryl)-1-ethyl-3,3-dimethyl-3H-indol-1-ium (CXL121): Yield 23%. 1H NMR (400 MHz, CDCl3, δppm): 8.30 (t, J = 8.6 Hz, 2H, Ar–H), 8.22 (d, J = 8.2 Hz, 1H, Ar–H), 7.56 (d, J = 10.4 Hz, 1H, Ar–H), 7.57–7.50 (m, 4H, Ar–H), 7.06 (t, J = 10.6 Hz, 2H, –CH=CH–), 5.05–5.00 (q, J = 14.4 Hz, 7.2 Hz, 2H, –NCH2CH3), 4.15 (t, J = 6.4 Hz, 2H, –O–CH2–CH2–), 3.52 (t, J = 8.6 Hz, 3H, –CH2Cl), 3.25–3.19 (m, 1H, –CH2Cl), 3.18–2.99 (m, 6H, N(CH2)3), 1.84 (s, 6H, –(CH3)2), 1.62 (t, J = 6.8 Hz, 3H, –CH2–CH3). 13C NMR (101 MHz, DMSO, δppm): 181.70, 162.16, 154.21, 153.84, 144.26, 140.90, 133.67, 130.10, 129.56, 128.61, 123.57, 116.22, 115.41, 110.95, 55.91, 52.58, 51.75, 28.81, 26.23, 22.53, 14.15. MS m/z (ESI): calcd for C26H33Cl2N2O+: 459.19; found 459.19.
(E)-2-(4-(2-(Bis(2-chloroethyl)amino)ethoxy)styryl)-3-ethyl-1,1-dimethyl-1H-benzo[e]indol-3-ium (CXL122): Yield 19%. 1H NMR (400 MHz, CDCl3, δppm): 8.32–8.19 (m, 4H, Ar–H), 8.12 (d, J = 8.6 Hz, 1H, Ar–H), 8.07 (t, J = 10.6 Hz, 1H, Ar–H), 7.84 (t, J = 8.4 Hz, 1H, Ar–H), 7.77–7.71 (m, 2H, Ar–H), 7.67 (t, J = 8.0 Hz, 1H, Ar–H), 7.09 (dd, J = 12.4 Hz, 8.2 Hz, 2H, –CH=CH–), 5.17 (q, J = 10.6 Hz, 8.4 Hz, 2H, –NCH2CH3), 4.16 (t, J = 8.8 Hz, 2H, –O–CH2–CH2–), 3.56 (t, J = 4.8 Hz, 3H, –CH2Cl), 3.19 (t, J = 12.0 Hz, 1H, –CH2Cl), 3.12–3.01 (m, 6H, N(CH2)3), 2.10 (s, 6H, –(CH3)2), 1.69 (t, J = 8.2 Hz , 3H, –CH2–CH3). 13C NMR (101 MHz, DMSO, δppm): 182.32, 163.12, 157.92, 153.89, 138.68, 133.71, 131.51, 131.14, 130.06, 128.82, 127.03, 123.51, 115.89, 115.46, 113.53, 109.74, 59.39, 57.46, 54.09, 53.74, 26.11, 14.34. MS m/z (ESI): calcd for C30H35Cl2N2O+: 509.21; found 509.22.