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With acetic acid In ethanol at 110℃; for 24 h; Inert atmosphere; Sealed tube
General procedure: The 2-aminobenzamide (1 equiv), the orthoester (2–3 equiv) and absolute ethanol (2–3 mL) wereplaced in a 15-mL Chemglass screw-cap pressure tube (No. CG-1880-01, Chemglass, Vineland, NJ,USA). Glacial acetic acid (3 equiv) was added, N2 was introduced to the vessel and the cap wastightened. The vessel was heated at 110 °C for 12–72 h, then cooled and concentrated to give thequinazolinone, which was purified by crystallization from absolute ethanol or trituration from 5percentether in pentane. The following compounds were prepared:
Reference：
[1] Molecules, 2018, vol. 23, # 11,
2
[ 123-54-6 ]
[ 5202-85-7 ]
[ 7142-09-8 ]
Yield
Reaction Conditions
Operation in experiment
81%
With ytterbium(III) triflate In 1,3,5-trimethyl-benzene at 60℃; for 24 h; Inert atmosphere
General procedure: 2-aminobenzamide (1, 1.0 mmol), 1,3-diketone (2, 1.5 mmol), Yb(OTf)3 (0.050 mmol, 5.0 molpercent),and mesitylene (2.0 mL) was placed in a 20-mL Pyrex flask equipped with a magnetic stirring bar and a reflux condenser under a flow of argon. The reaction was carried out at 60°C (bath temp.) for 24 h with stirring. The reaction mixture was then cooled to room temperature and analyzed by GLCand GC-MS. The product 3 was isolated by medium-pressure column chromatography on silica gel(eluent: EtOAc/hexane = 30/70 ~ EtOAc 100percent. For 3j, eluent: MeOH/CHCl3 = 30/70 ~ 50/50) andrecrystallization from MeOH/hexane. The products 3l and 3m were isolated by recrystallizationfrom EtOAc/hexane. 1H NMR spectra were recorded at 400 MHz, and 13C NMR spectra wererecorded at 100 MHz in DMSO-d6 (For 3j, in a mixture of DMSO-d6 and methanol-d4). Elemental analyses were performed at the Microanalytical Center of Kyoto University. The analytical and spectral data of 3a,10 3b-c,11 3d,12 3e,13 3f,14 3g-h,10 and 3j-l,7 are fully consistent with those reported previously. The products 3i,15 and 3m16 were characterized below.
Part B: The preparation of 6-chloro-2,4-quinazoline-dione. Urea (2.64 g) and 5-chloro-2-amino benzamide (3.75 g) were dissolved in 100 mL of pyridine. To this solution was added 10percent HCl (aq.) (6 drops) and the resulting solution was refluxed for 12-18 hours. The reaction mixture was evaporated to dryness and the resulting residue was suspended in 125 mL of water. The pH of the suspension was adjusted to 6 with dilute hydrochloric acid and the solid was recovered by filtration. The filter cake was washed well with water and was dried to yield 3.27 g of buff powder (76percent): 1 H NMR (DMSO-d6, 300 MHz) δ11.45 (s, 1H), 11.25 (s, 1H), 7.81 (d, 1H), 7.66 (dd, 1H), 7.18 (d, 1H).
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