Synthesis and anticancer activity of diam(m)ine platinum(II) complexes
MeOH (20 ml) over 10 min. The reaction mixture was stirred at 50 °C. TLC analysis
confirmedformationofproduct.Themethanolwasdistilledunderreducedpressure.The
aqueous layer was extracted with 2 9 25 ml of ethyl acetate to remove organic
impurities. Then the aqueous phase was adjusted to pH = 1 with diluted hydrochloric
acid and extracted with ethyl acetate (3 9 30 ml). The combined organic extracts were
washed with brine (3 9 30 ml), dried over Na2SO4, and evaporated under reduced
pressure. The crude product was recrystallized from water (5 ml) to give 3-oxo-1,1-
cyclobutane dicarboxylic acid (1.1 g, 76.29 % yield) as a pale yellow solid. Mp:
1
142–146 °C. H NMR (400 MHz, CDCl3, d): 3.75 (s, 4H). 13C NMR (100 MHz,
DMSO-d6, d): 33.4 (2C), 48.3, 170.4(2C), 172.6. IR (KBr, cm-1): 3,943, 3,865, 3,742,
3,102, 2,961, 1,731, 1,411, 1,285, 1,189, 861, 446. MS–ESI1 m/z: 157([M–H]-,
100 %).
General procedures for the synthesis of complexes 1–4
The synthetic procedures in the presence of platinum complexes were carried out in
a light-tight environment. K2[PtCl4] (10 g, 28 mmol) was dissolved in water
(100 ml) and treated with KI (20.9 g, 126 mmol). After standing for 40 min at room
temperature, a solution of NH3 (34 mmol in 50 ml water) or diamine (28 mmol in
50 ml water) was added dropwise while stirring, yielding the corresponding
intermediate cis-[PtA2I2] (A2 = 2NH3 or diamine) and the intermediate was
filtrated off, washed with water and ethanol, and dried in vacuo at 55 °C. To a
suspension of cis-[PtA2I2] (6.00 mmol) in 150 ml of distilled water, freshly
prepared disilver 3-oxo-cyclobutane-1,1-dicarboxylate (12 mmol) was added and
mixed for 36 h with stirring at 37 °C. After AgI was filtrated off, the solution was
concentrated at 45 °C in vacuo to 20 ml to give a white crystalline product. It was
collected, washed successively with icy water and ethanol, and dried under reduced
pressure at 45 °C.
1
Complex 1 H NMR (400 MHz, DMSO-d6, d): 3.75 (s, 4H), 4.22 (s, 6H). 13C
NMR (100 MHz, DMSO-d6, d): 46.5 (2C), 55.9, 175.7 (2C), 205.8. IR (KBr, cm-1):
3,291 (s, vN–H), 1,782 (s, vC=O), 1,630 (vs, vas (COO)), 1,368 (vs, va(COO)), 454 (w,
v
Pt–N). MS–ESI1 m/z: 408 ([M ? Na]?, 100 %). Anal. calcd for C6H10N2O5Pt: C,
18.7; H, 2.60; N, 7.27; Pt, 50.7 %. Found C, 18.5; H, 2.62; N, 7.28; Pt, 50.4 %.
Complex 2 1H NMR (400 MHz, DMSO-d6, d): 0.93, 1.20 (m, 4H, cyclohexane),
1.44, 1.78 (m, 4H, cyclohexane), 2.03 (2H, cyclohexane), 3.71 (4H, cyclobutane),
5.27, 5.97 (4H, 2NH3). 13C NMR (100 MHz, DMSO-d6, d): 24.1(2C), 31.5(2C),
46.4(2C), 55.9(2C), 62.1, 175.6(2C), 206.6. IR (KBr, cm-1): 3,229 (s, vN–H),
2,941(w, vC–H), 1,797 (s, vC=O), 1,635 (vs, vas (COO)), 1,363 (vs, va(COO)), 454 (w, vPt-
N). MS–ESI1 m/z: 488 ([M ? Na]?, 100 %). Anal. calcd for C12H18N2O5Pt: C,
31.0; H, 3.87; N, 6.02; Pt, 41.9. Found C, 31.3; H, 3.91; N, 6.08; Pt, 41.4 %.
Complex 3 13C NMR (100 MHz, DMSO-d6, d): 16.6, 16.7, 31.4, 46.5, 47.9,
48.2, 55.6, 56.2, 77.9, 79.6, 107.0, 175.8(2C), 206. IR (KBr, cm-1): 3,253(s, vN–H),
2,967(w, vC–H), 1,783(s, vC=O), 1,628 (vs, vas (COO)), 1,383 (vs, va(COO)), 456 (w,
v
Pt–N). MS–ESI1 m/z: 548.0967 ([M ? Na]?, 42 %). Anal. calcd for C14H22N2-
O7Pt: C, 32.0; H, 4.19; N, 5.33; Pt, 37.2. Found C, 30.8; H, 3.90; N, 6.00; Pt,
41.6 %.
123