A short and facile synthesis of a series of 3-aryl-3,4-dihydroquinazolin-2(1H)-ones was accomplished in good yields via the novel reductive cyclisation of 2-nitrobenzylamines with bis(trichloromethyl)carbonate (triphosgene) promoted by TiCl4/Sm system. The structures of the products were characterised by IR, 1H NMR and elemental analysis and the structure of 3a was confirmed by X-ray diffraction analysis.
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ShiD.Q., ShiC.L., WangX.S., ZhuangQ.Y., TuS.J., and HuH.W., Synlett, 2004, 2239.
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Crystal suitable for X-ray analysis was obtained by slow evaporation of an EtOH solution of 3a. C15H14N2O, M = 238.28, triclinic, space group P-1, a = 6.344(1), b = 9.504(1), c = 10.726(2) Å, α = 78.92(1)°, β = 83.04(1) °, γ = 78.91(1)°, V = 620.38(18) Å3, Z = 2, ρcalcd = 1.276 g·cm−3, F(000) = 252, μ(MoKα) = 0.082 mm−1, colourless block crystals, crystal size 0.60 mm x 0.50 mm x 0.20 mm. Intensity data were collected at 296K on a Siemens P4 diffractometer with graphite-monochromated MoKα radiation (l = 0.71073 Å): 2311 independent reflections were collected using w scan mode in the range of 1.94° to 25.49°, of which 1395 intensity data with [I>2σ (I)] were observed. The corrections for Lp factors were applied. The structure was solved by direct methods and expanded using Fourier techniques. Non-hydrogen atoms were refined anisotropically Hydrogen atoms were introduced in the F value calculation but fixed during the structure refinement. A full matrix least-squares refinement gave final R1 = 0.0452 and wR2 = 0.1146, with w = 1/[σ2(Fo2) + (0.0668P)2] where P = (Fo2 + 2Fc2)/3, S = 0.957. The maximum peak in the final difference Fourier map was 0.150 e/Å3 and the minimum peak was −0.126 e/Å3. All calculations were performed using TEXSAN program package. Full crystallographic data has been deposited at the Cambridge Crystallographic Data Centre, deposition number CCDC 659078. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1E2, UK (fax: (+ 44)1223-336-033; E-mail: deposit@ccdc.cam.ac.uk).
