NMR spectra were recorded on a Bruker AVANCE II spectrometer (400 MHz) with TMS as internal standard. Elemental analyses were performed by the Elemental Analysis Group of the I.Ya. Postovsky Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences (Yekaterinburg). Mass spectra were recorded on a Bruker Daltonics MicrOTOF-Q II series spectrometer with electrospray ionization. The mass spectrum of compound 8 was recorded on a Shimadzu GCMS-QP2010 Ultra spectrometer with electron impact ionization (EI). Single crystal X-ray diffraction analysis of compound 6e was performed on an automatic four-circle Rigaku XtaLAB Synergy diffractometer with a HyPix-6000HE CCD detector and a PhotonJet X-ray source; X-ray diffraction analysis of compound 6d was performed on an automatic four-circle Xcalibur 3 X-ray diffractometer with a CCD detector, both according to standard procedures (MoKα radiation, graphite monochromator, ω-scanning with 1° step) at 293(2) K. An empirical absorption correction was applied. The measured reflection data were indexed, integrated, and scaled using the CrysAlisPro software package [34]. The structures were solved by direct methods using SHELXT [35] and refined by full-matrix least-squares on F2 using SHELXL software package [36]. Structure solution and refinement were performed in the Olex2 software environment [37]. Non-hydrogen atoms were refined anisotropically. Hydrogen atoms attached to oxygen atoms were located from Fourier difference maps. All other hydrogen atoms were placed in calculated positions according to stereochemical criteria and refined using a rider model. The results of X-ray diffraction analysis were deposited with the Cambridge Crystallographic Data Centre under deposition numbers CCDC 2473917 (6e) and CCDC 2473909 (6d).

The reaction progress and product purity were monitored by TLC on Silica gel on TLC Al foils plates. Products were purified by column chromatography on Sigma-Aldrich silica gel (230-400 mesh). UV/Vis absorption spectra were recorded on a Shimadzu 1200 spectrophotometer. Luminescence spectra were recorded on a Horiba-Fluoromax-4 spectrofluorimeter or an FLS1000-SS time-resolved fluorescence spectrometer.

Compounds 1, 2, and 5 are commercially available; compound 3 was prepared according to a previously described procedure for similar compounds [38].

(E)-2-benzamide (3). Yield 1125 mg (4.16 mmol, 91%). 4-Methylthiobenzaldehyde (700 mg, 4.60 mmol) and anthranilamide (626.1 mg, 4.60 mmol) were dissolved in alcohol and stirred for 12 h under reflux, after which the solvent was distilled off under reduced pressure. 1H NMR spectrum (DMSO-d6), δ, ppm: 2.55 s (3H, SСН3), 7.21–7.23 m (1H, CHAr), 7.31–7.35 m (1H, CHAr), 7.41–7.43 m (2H, C6H4SCH3), 7.52–7.56 m (1H, CHAr), 7.6 br. s (1H, NH2), 7.87–7.89 m (2H, C6H4SCH3), 7.92–7.94 m (1H, CHAr), 8.3 br. s (1H, NH2), 8.55 s (1H, NCH).

2-(4-(Methylthio)phenyl)quinazolin-4(3H)-one (4). Yield 950 mg (3.54 mmol, 85%). The starting substrate 3 (1125 mg, 4.16 mmol) was dissolved in a mixture of 50 mL of 1,2-dichloroethane and 10 mL of ethanol, then 1511.4 mg of DDQ (6.66 mmol) was added to the solution. The reaction mixture was stirred under reflux for 12 h. The product was isolated by flash chromatography on Al2O3, eluent—ethyl acetate. 1H NMR spectrum (DMSO-d6), δ, ppm: 2.56 s (3H, SСН3), 7.34–7.37 m (2H, C6H4SCH3), 7.44–7.48 m (1H, quinazolinone), 7.46–7.70 m (1H, quinazolinone), 7.76–7.79 m (1H, quinazolinone), 8.13–8.15 m (1H, quinazolinone), 8.18–8.20 m (2H, C6H4SCH3), 12.39 s (1H, NCH).

General procedure for S-arylation of 2-[4-(methylthio)phenyl]quinazolin-4(3H)-one (4). The starting quinazolinone 4 was dehydrated using dry toluene. The dried quinazolinone 4 (200 mg, 0.75 mmol) was placed into a two-necked flask and dissolved in anhydrous 1,4-dioxane (30 mL), then isoamyl nitrite (0.3 mL, 2.24 mmol) was added. The corresponding anthranilic acid (440 mg, 2.24 mmol) was dissolved in 10 mL of anhydrous 1,4-dioxane and placed in a dropping funnel with back pressure. The resulting solution of quinazolinone 4 was heated to 101°C under an argon atmosphere, after which the anthranilic acid 5 solution was added dropwise over 10 min. After complete addition of the anthranilic acid, the resulting mixture was kept at 101°C for 1 h. 1,4-Dioxane was distilled off under reduced pressure. The resulting mixture was dissolved in 50 mL of methylene chloride and washed with aqueous sodium hydroxide solution (3 × 30 mL). The product was isolated by column chromatography on silica gel, eluent—CH2Cl2–ethyl acetate (95 : 5), Rf 0.2. An analytical sample was obtained by recrystallization from methanol.

2-[4-(Phenylthio)phenyl]quinazolin-4(3H)-one (6a). Yield 63 mg (0.19 mmol, 26%). 1H NMR spectrum (DMSO-d6), δ, ppm: 7.30–7.32 m (2H, Ph), 7.39–7.46 m (6H, Ph, C6H4, quinazolinone), 7.65–7.67 m (1H, quinazolinone), 7.74–7.78 m (1H, quinazolinone), 8.12–8.14 m (1H, quinazolinone), 8.18–8.20 m (2H, C6H4), 12.4 br. s (1H, NH). 13C NMR spectrum (CDCl3), δC, ppm: 120.7, 126.4, 126.8, 128.0, 128.1, 128.3, 129.2, 129.6, 130.5, 133.0, 133.4, 135.0, 142.2, 149.6, 151.2, 164.2. Mass spectrum, m/z (Irel, %): 330.18 (100) [М + Н]+. Found, %: С 72.60; Н 4.29; N 8.41. C20H14N2OS. Calculated, %: С 72.70; Н 4.27; N 8.48.

2-quinazolin-4(3H)-one (6b). Yield 69 mg (0.19 mmol, 25%). 1H NMR spectrum (CDCl3), δ, ppm: 7.21–7.27 m (2H, C6H3F2), 7.33–7.36 m (1H, C6H3F2), 7.43–7.44 m (2H, C6H4), 7.55–7.57 m (1H, quinazolinone), 7.85–7.88 m (1H, quinazolinone), 7.95–7.97 m (1H, quinazolinone), 8.19–8.20 m (2H, C6H4), 8.31–8.33 m (1H, quinazolinone), 11.3 br. s (1H, NH). 13C NMR spectrum (CDCl3), δC, ppm: 120.0 d. d (J 343.8, 17.7 Hz), 120.9, 126.4, 127.0, 128.1 (2С), 129.0, 129.6 (2С), 130.0, 149.4, 151.8, 131.2, 134,8, 140.9, 149.5, 150.8, 163.7. 19F NMR spectrum (CDCl3), δF, ppm: –136.55, –134.98. Mass spectrum, m/z (Irel, %): 367.06 (100) [М + Н]+. Found, %: С 65.65; Н 3.35; N 7.68. C20H12F2N2OS.Calculated, %: С 65.56; Н 3.30; N 7.65.

2-quinazolin-4(3H)-one (6c). Yield 79 mg (0.22 mmol, 29%). 1H NMR spectrum (CDCl3), δ, ppm: 2.31–2.34 m (6H, CH3), 7.20–7.22 m [2H, C6H3(CH3)2], 7.34–7.38 m [3H, C6H4, C6H3(CH3)2], 7.48–7.53 m (1H, quinazolinone), 7.81–7.82 m (2H, quinazolinone), 8.09–8.12 m (2H, C6H4), 8.30–8.33 m (1H, quinazolinone), 11.2 br. s (1H, NH). 13C NMR spectrum (CDCl3), δC, ppm: 19.6, 19.7, 120.8, 126.4, 126.7, 127.8, 127.9, 128.1, 129.0, 129.8, 130.9, 131.4, 134.9 (2С), 137.6, 138.2, 143.6, 149.6, 151.3, 163.9. Mass spectrum, m/z (Irel, %): 359.11 (100) [М + Н]+. Found, %: С 73.67; Н 5.09; N 7.81. C22H18N2OS. Calculated, %: С 73.71; Н 5.05; N 7.82.

2-quinazolin-4(3H)-one (6d). Yield 121 mg (0.31 mmol, 42%). 1H NMR spectrum (CDCl3), δ, ppm: 3.90 s (3H, OCH3), 3.97 s (3H, OCH3), 6.95–6.97 d [1H, C6H3(OMe)2, 3J 8.0 Hz], 7.09–7.10 d [1H, C6H3(OMe)2, 4J 2.0 Hz], 7.19–7.22 d. d [1H, C6H3(OMe)2, 3J 8.0, 4J 2.0 Hz], 7.29–7.33 m (2H, C6H4), 7.48–7.54 m (1H, quinazolinone), 7.81–7.84 m (2H, quinazolinone), 8.08–8.11 m (2H, C6H4), 8.31–8.33 m (1H, quinazolinone), 11.1 br. s (1H, NH). 13C NMR spectrum (CDCl3), δC, ppm: 56.1, 56.2, 113.3, 118.1, 121.4, 121.4, 126.3, 126.6, 126.9, 127.9, 128.3, 128.9, 130.1, 135.1, 143.6, 149.2, 150.0, 150.5, 152.2, 162.7. Mass spectrum, m/z (Irel, %): 391.10 (100) [М + Н]+. Found, %: С 67.71; Н 4.71; N 7.13. C22H18N2O3S. Calculated, %: С 67.67; Н 4.65; N 7.17. Crystals suitable for X-ray ray diffraction analysis were obtained by slow evaporation of acetonitrile solution. Crystallographic data: C22H18N2O3S, M 390.44, triclinic crystal system, space group P-1; unit cell parameters: a = 8.0894(2) Å, b = 9.0804(2) Å, c = 16.5654(3) Å, α = 105.578(2)°, β = 94.327(2)°, γ = 100.619(2)°, V = 1141.96(5) Å3, Z = 2, T = 293(2) K, μ(MoKα) = 0.71073 mm–1, dcalc = 1.135 g/cm3, sample size 0.54 × 0.28 × 0.07 mm. Number of measured reflections was 44398 (4.84° ≤ 2θ ≤ 44.7760°). Number of independent reflections was 5705 (Rint = 0.0947). Number of reflections with I > 2σ(I) was 2828. Final refinement parameters: R1 = 0.1022, wR2 = 0.2789 [for reflections with I > 2σ(I)], R1 = 0.1761, wR2 = 0.3569 (for all reflections). Maximum and minimum residual electron density peaks were 1.226/–0.370.

2-[4-(Naphthalen-2-ylthio)phenyl]quinazolin-4(3H)-one (6e). Yield 126 mg (0.33 mmol, 44%). 1H NMR spectrum (CDCl3), δ, ppm: 7.45–7.58 m (6H, Naphth, C6H4), 7.81–7.91 m (5H, quinazolinone, Naphth), 8.06–8.06 m (1H, quinazolinone), 8.11–8.14 m (2H C6H4), 8.29–8.32 m (1H, quinazolinone), 11.1 br. s (1H, NH). 13C NMR spectrum (CDCl3), δC, ppm: 121.4, 126.3, 127.0, 127.5, 127.5, 127.8, 128.1, 128.2, 128.9, 129.1, 130.0, 130.1, 130.1, 131.3, 132.5, 132.9, 133.9, 135.1, 141.1, 149.1, 152.2, 162.7. Mass spectrum, m/z (Irel, %): 381.10 (100) [М + Н]+. Found, %: С 75.79; Н 4.25; N 7.39. C24H16N2OS. Calculated, %: С 75.77; Н 4.24; N 7.36. Crystals suitable for X-ray diffraction analysis were obtained by slow evaporation of acetonitrile solution. Crystallographic data: C24H16N2OS, M 380.493, monoclinic crystal system, space group P121/n1; unit cell parameters: a = 12.9632(3) Å, b = 5.6596(2) Å, c = 31.8951(10) Å, β = 97.930(3)°, V = 2317.66(12) Å3, Z = 4, 293(2) K, μ(MoKα) = 0.71073 mm–1, dcalc = 1.090 g/cm3, sample size 0.73 × 0.09 × 0.06 mm. Number of measured reflections was 78033 (5.1440° ≤ 2θ ≤ 45.6240°). Number of independent reflections was 6035 (Rint = 0.1045). Number of reflections with I > 2σ(I) was 2836. Final refinement parameters: R1 = 0.0550, wR2 = 0.1571 [for reflections with I > 2σ(I)], R1 = 0.1218, wR2 = 0.2206 (for all reflections). Maximum and minimum residual electron density peaks 0.3812/–0.3382.

2-[4-(Methylthio)phenyl]-4-phenylquinazoline (8). Yield 985 mg (3 mmol, 60%). A mixture of 2-aminobenzophenone (1 g, 5 mmol), 4-methylthiobenzaldehyde (0.76 g, 5 mmol), ammonium acetate (1.54 g, 20 mmol), and molecular iodine (1.27 g, 5 mmol) in EtOH (40 mL) was stirred at room temperature for 24 h. The formed precipitate was filtered off and washed with water and EtOH. The product was used in the next step without further purification. 1H NMR spectrum (DMSO-d6), δ, ppm: 2.57 s (3H, SCH3) 7.35–7.37 m (2H, C6H4SCH3), 7.60–7.64 m (4H, quinazoline, C6H5), 7.85–7.86 m (2H, C6H5), 7.94–7.98 m (1H, quinazoline), 8.07–8.11 m (2H, quinazoline), 8.55–8.57 m (2H, C6H4SCH3). 13C NMR spectrum (CDCl3), δC, ppm: 14.2 (SCH3), 120.9, 125.4, 126.8, 127.6, 128.5, 128.6, 129.9, 150.1, 133.8, 134.3, 137.0, 141.9, 151.2, 158.7, 167.9. Mass spectrum (EI), m/z (Irel, %): 329 (26) [М + 1]+, 328 (100) [М]+. Found, %: C 76.80; H 4.91; N 8.53. C21H16N2S. Calculated, %: С 76.76; Н 4.99; N 8.41.

2-[4-(Phenylthio)phenyl]-4-phenylquinazoline (9). Yield 120 mg (0.31 mmol, 50%). 1H NMR spectrum (CDCl3), δ, ppm: 7.32–7.38 m (3H, Ph), 7.45–7.48 m (4H, Ph), 7.35–7.63 m (4H, quinazoline, Ph, C6H4), 7.89–7.93 m (3H, quinazoline, Ph), 8.14–8.17 m (2H, quinazoline), 8.63–8.65 m (2H, C6H4). 13C NMR spectrum (CDCl3), δC, ppm: 121.7, 127.1, 127.6, 128.6, 129.2, 129.4, 130.0, 130.1, 130.2, 131.9, 133.6, 134.8, 136.7, 137.7, 139.4, 152.0, 159.7, 169.4. Mass spectrum, m/z (Irel, %): 391.12 (100) [М + Н]+. Found, %: С 79.91; Н 4.72; N 7.21. C26H18N2S. Calculated, %: С 79.97; Н 4.65; N 7.17.