Molecules 2014, 19
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N-Methylsuccinimide (2b). N-Methylmaleimide (27.8 mg, 0.25 mmol) and TiO2 (30 mg, 0.38 mmol)
in CH3OH (3 mL) and CH3CN (27 mL) were reacted in accordance with the general procedure.
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Following irradiation for 17 h 2b was obtained as an off white powder (25.5 mg, 90%). H-NMR
(300 MHz, CDCl3, 298 K): δ = 2.69 (s, 4H), 2.97 (s, 3H); 13C-NMR (75 MHz, CDCl3, 299 K):
δ = 24.8, 28.2, 177.3. Consistent with the literature [28].
1-Phenylpyrrolidine-2,5-dione (2c). N-Phenyl maleimide (0.0347 g, 0.2 mmol) and TiO2 (0.012 g,
0.15 mmol) were added to methanol (1.1 mL) and acetonitrile (10.9 mL). Following irradiation for
20 h, 2c was obtained as an off white solid (0.33 g, 94%). 1H-NMR (400 MHz, CDCl3): δ 2.90 (4H, s),
7.20–7.22 (2H, m), 7.30–7.35 (1H, m), 7.37–7.43 (2H, m). 13C-NMR (75 MHz, CDCl3, 297 K):
δ = 28.4, 126.5, 128.7, 129.2, 132.0, 176.3. Spectral data was consistent with literature [29].
N-Carboxymethylsuccinimide (2d). N-Carboxymethylmaleimide (38.8 mg, 0.25 mmol) and TiO2
(30 mg, 0.38 mmol) in CH3OH (3 mL) and CH3CN (27 mL) were reacted in accordance with the general
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procedure. Following irradiation for 15 h 2d was obtained as colorless oil (32.1 mg, 82%). H-NMR
(400 MHz, CDCl3, 296 K): δ = 2.81 (s, 4H), 3.96 (s, 3H); 13C-NMR (75 MHz, CDCl3, 299 K):
δ = 28.6, 172.6, 176.4.
Succinic anhydride (4). Maleic anhydride (24.5 mg, 0.25 mmol) and TiO2 (30 mg, 0.38 mmol) in
CH3OH (3 mL) and CH3CN (27 mL) were reacted in accordance with the general procedure.
Following irradiation for 15 h, 4 was observed by 1H-NMR (60% w.r.t. a CH2Br2 standard). 1H-NMR
(300 MHz, CDCl3, 296 K): δ = 3.00 (s, 4H). 4-Oxobutanoic acid was observed in the same manner
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(17%). H-NMR (300 MHz, CDCl3, 296 K): δ = 2.59–2.70 (m, 4H), 3.69 (s, 3H), 9.86 (br-s, 1H).
Spectral data for both compounds consistent with literature [30].
3-Methyl-1-phenylpyrrolidine-2,5-dione (6b). From 3-methyl-1-phenyl-1H-pyrrole-2,5-dione (0.037 g,
0.2 mmol) and TiO2 (0.12 g, 0.15 mmol). Following irradiation for 20 h, 6b was obtained as an off
white solid, 1H-NMR (wrt CH2Br2 internal standard) revealed 97% conversion of the starting material
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and ≤5% yield of the product. H-NMR (400 MHz, CDCl3): δ 1.47 (3H, m), 2.55 (1H, m), 3.07–3.09
(1H, m), 3.15–3.19 (1H, m), 7.25–7.51 (5H, m). Spectral data was consistent with literature [31].
3,4-Dimethyl-1-phenylpyrrolidine-2,5-dione (6c). 3,4-Dimethyl-N-phenylmaleimide 5c (0.0402 g,
0.2 mmol) and TiO2 (0.12 g, 0.15 mmol) were added to a solution of methanol (1.1 mL) and
acetonitrile (10.9 mL). Following irradiation for 20 h, 6c was obtained as an off white solid, 1H-NMR
(wrt CH2Br2 internal standard) revealed 50% conversion of the starting material and 17% yield of the
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product. H-NMR (400 MHz, CDCl3): δ 1.45 (6H, d, J = 7.0 Hz), 2.60 (2H, m), 7.31–7.32 (2H, m),
7.35–7.37 (2H, m), 7.47–7.49 (2H, m). Spectral data was consistent with literature [26].
1,3-Diphenylpyrrolidine-2,5-dione (6d). From 1,3-diphenyl-1H-pyrrole-2,5-dione (0.049 g, 0.2 mmol)
and TiO2 (0.12 g, 0.15 mmol). Following irradiation for 20 h, 6d was obtained as an off white solid,
1H-NMR (wrt CH2Br2 internal standard) revealed 99% conversion of the starting material and 9%
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yield of the product. H-NMR (400 MHz, CDCl3): δ 3.02 (1H, dd, J = 23.4 and 4.8), 3.36 (1H, dd,
J = 9.9 and 18.7 Hz), 4.2 (1H, m), 7.37–7.51 (10H, m).