Synthesis of N-2-(substituted phenyl)-3-(naphthalen-6-yl) thiazolidin-4-one (5a–g)
A mixture of compound (3a–g, 0.01 mol) and thioglycollic acid (0.01 mol) was refluxed on a heating mantle at 120–125 °C for approximately 12 h. The reaction mixture was cooled and treated with 10% sodium bicarbonate solution. The product was isolated and re-crystallized from methanol–dioxane (4:1). The overall reaction scheme followed is depicted in Scheme 1.
4-(naphthalen-3-ylimino methyl) phenol 3a
Molecular formula C17H13NO; melting point 116–117 °C; yield 60%. Infrared (IR) (KBr, cm−1) 3,045.0 (CH), 1,440–1,514 (–H–C=N). 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 8.2 (s, 1H, CH), 4.9 (s, 1H, OH), 6.7–7.4 (m, 11H, Ar–H). 13C-NMR (300 MHz, CDCl3) δ: 160.6, 150.4, 135.2, 132.4, 130, 129.4, 128.2, 126.4, 120.4, 119.2, 116.
3,4,5-trimethoxybenzylidenenaphthalen-2-amine 3b
Molecular formula C20H19NO3; melting point 131–132 °C; yield 60%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.7 (s, 9H, OCH3), 8.3 (s, 1H, CH), 6.6–7.4 (m, 9H, Ar–H). 13C-NMR (300 MHz, CDCl3) δ: 160.4, 150.6, 141.5, 135, 132.2, 129.4, 128.2, 126.2, 120.6, 119.2, 106.2, 56.2.
3,4-dimethoxybenzylidene naphthalen-2-amine 3c
Molecular formula C19H17NO2; melting point 128–130 °C; yield 60%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.6 (s, 6H, OCH3), 8.1 (s, 1H, CH), 6.7–7.6 (m, 10H, Ar–H).
2-methoxy-4-(naphthalen-3-ylimino methyl) phenol 3d
Molecular formula C18H15NO2; melting point 114–115 °C; yield 60%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.7 (s, 3H, OCH3), 5.0 (s, 1H, OH), 8.2 (s, 1H, CH), 6.7–7.4 (m, 10H, Ar–H). 13C-NMR (300 MHz, CDCl3) δ: 160.1, 151.4, 150.2, 148, 135.2, 132.2, 129.4, 128, 127.4, 123, 120.4, 119.2, 117, 114.8, 56.
Benzylidenenaphthalen-2-amine 3e
Molecular formula C17H13N; Melting point 106–107 °C; Yield 60%; 1HNMR (300 MHz, CDCl3, TMS = 0) δ: 8.1 (s, 1H, CH), 7.2–7.6 (m, 12H, Ar–H).
3-nitrobenzylidenenaphthalen-2-amine 3f
Molecular formula C17H12N2O2; melting point 122–123 °C; yield 70%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 8.5 (s, 1H, Ar–H), 8.3 (s, 1H, CH), 8.1–8.2 (d, 2H, Ar–H), 7.3–7.6 (m, 8H, Ar–H).
4-chlorobenzylidenenaphthalen-2-amine 3g
Molecular formula C17H12ClN; melting point 124–125 °C; yield 65%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 8.1 (s, 1H, CH), 7.3–7.6 (m, 11H, Ar–H).
3-chloro-4-(4-hydroxyphenyl)-1-(naphthalen-3-yl)azetidin-2-one 4a
Molecular formula C19H14ClNO2; melting point 146–147 °C; yield 60%; IR (KBr, cm−1) 3,450.5 (NH), 3,047.0 (CH), 1,754.1 (C=O), 1,624.9 (CO–NH), 1,448.7 (CN), 896.5, 750.5 and 677.8(C=C), 679.8 (C–Cl). 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 5.0 (s, 1H, OH), 5.2 (d, 1H, CH), 5.4 (d, 1H, CH), 6.8–7.4 (m, 11H, Ar–H). 13C-NMR (300 MHz, CDCl3) δ: 162.1, 156.4, 141.2, 136.4, 133.2, 128, 127.4, 126.1, 125.4, 124, 121.4, 118.2, 115, 108.6, 63, 62.2.
3-chloro-4-(3,4,5-trimethoxyphenyl)-1-(naphthalen-3-yl)azetidin-2-one 4b
Molecular formula C22H20ClNO4; melting point 134–135 °C; yield 60%; 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.5 (s, 9H, OCH3), 5.1 (d, 1H, CH), 5.4 (d, 1H, CH), 6.1 (s, 2H, Ar–H), 6.7–7.5 (m, 7H, Ar–H). 13C-NMR (300 MHz, CDCl3) δ: 162.2, 150.3, 141.2, 137.2, 133.2, 127.4, 126.5, 125.3, 124.2, 121.4, 118.1, 108.2, 104, 63, 62.2, 56.
3-chloro-4-(3,4-dimethoxyphenyl)-1-(naphthalen-3-yl)azetidin-2-one 4c
Molecular formula C21H18ClNO3; melting point 128–130 °C; yield 60%.; IR (KBr, cm−1): 3,228.0 (N–H), 3,045.0 (C–H), 1,749.4 (C=O), 1,672.2 (CO–NH), 1,420.0 (C–N), 832.8 and 779.8 (C–C), 689.2 (C–Cl). 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.6 (s, 6H, OCH3), 5.2 (d, 1H, CH), 5.3 (d, 1H, CH), 6.6–7.6 (m, 10H, Ar–H).
3-chloro-4-(4-hydroxy-3-methoxyphenyl)-1-(naphthalen-3-yl)azetidin-2-one 4d 22
Molecular formula C20H16ClNO3; melting point 134–135 °C; yield 60%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.7 (s, 3H, OCH3), 4.9 (s, 1H, OH), 5.1 (d, 1H, CH), 5.4 (d, 1H, CH), 6.6–7.4 (m, 10H, Ar–H). 13C–NMR (300 MHz, CDCl3) δ: 162.1, 151.2, 143.2, 141.4, 137.2, 133.2, 127.4, 126.5, 125.3, 124.3, 121.4, 120.6, 118.1, 116, 112.2, 108.2, 63, 62.2, 56.2.
3-chloro-1-(naphthalen-3-yl)-4-phenylazetidin-2-one 4e
Molecular formula C19H14ClNO; melting point 118–119 °C; yield 60%. IR (KBr, cm−1): 3,469.6 (NH), 3,054.0 (CH), 1,756.8 (C=O), 1,670.8 (CO–NH), 1,444.4 (C–N), 854.5, 679.2(C=C), 689.2 (C–Cl). 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 5.1 (d, 1H, CH), 5.4 (d, 1H, CH), 6.8–7.4 (m, 12H, Ar–H).
3-chloro-1-(naphthalen-3-yl)-4-(3-nitrophenyl)azetidin-2-one 4f
Molecular formula C19H13ClN2O3; melting point 122–124 °C; yield 70%. IR (KBr, cm−1): 3,449.5 (NH), 3,045.0 (CH); 1,757.1 (C=O), 1,622.9 (CO–NH), 1,446.7(CN), 894.5, 750.5 and 677.8 (C=C), 677.8 (C–Cl). 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 5.4 (d, 1H, CH), 5.2 (d, 1H, CH), 6.8–7.5 (m, 9H, Ar–H), 8.0–8.1(m, 2H, Ar–H).
3-chloro-4-(4-chlorophenyl)-1-(naphthalen-3-yl)azetidin-2-one 4g
Molecular formula C19H13Cl2NO; melting point 128–129 °C; yield 65%; IR (KBr, cm−1): 3,238.0 (N–H), 3,049.0 (C–H), 1,750.4 (C=O), 1,673.2 (CO–NH), 1,422.0 (C–N), 834.5 and 779.8 (C–C), 619.9 (C–Cl). 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 5.4 (d, 1H, CH), 5.1 (d, 1H, CH), 6.8–7.4 (m, 11H, Ar–H).
4-(4-hydroxyphenyl)-3-(naphthalen-3-yl)thiazolidin-2-one 5a
Molecular formula C19H15NO2S; melting point 126–127 °C; yield 60%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 5.0 (s, 1H, OH), 4.8 (t, 1H, CH), 3.25 (dd, 2H, J = 5.6 Hz, CH2), 6.8–7.4 (m, 11H, Ar–H). 13C–NMR (300 MHz, CDCl3) δ: 170.1, 156.4, 141.2, 136.4, 133.2, 128, 127.4, 126.1, 125.4, 124, 121.4, 118.2, 115, 108.6, 55, 35.2.
4-(3,4,5-trimethoxyphenyl)-3-(naphthalen-3-yl)thiazolidin-2-one 5b
Molecular formula C22H21NO4S; melting point 128–130 °C; yield 65%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.25(dd, 2H, J = 5.6 Hz, CH2), 3.7 (s, 9H, OCH3), 5.2 (t, 1H, CH), 6.2–7.4 (m, 9H, Ar–H).
4-(3,4-dimethoxyphenyl)-3-(naphthalen-3-yl)thiazolidin-2-one 5c
Molecular formula C21H19NO3S; melting point 133–134 °C; yield 58%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3. 27 (dd, 2H, J = 5.7 Hz, CH2), 3.7 (s, 6H, OCH3), 5.2 (t, 1H, CH), 6.6–7.4 (m, 10H, Ar–H).
4-(4-hydroxy-3-methoxyphenyl)-3-(naphthalen-3-yl)thiazolidin-2-one 5d 22
Molecular formula C20H17NO3S; melting point 137–138 °C; yield 55%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.32 (dd, 2H, J = 5.6 Hz, CH2), 3.6 (s, 3H, OCH3), 4.9 (s, 1H, OH), 5.1 (t, 1H, CH), 6.6–7.4 (m, 10H, Ar–H).
3-(naphthalen-3-yl)-4-phenylthiazolidin-2-one 5e
Molecular formula C19H15NOS; melting point 134–135 °C; yield 68%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.34 (dd, 2H, J = 5.8 Hz, CH2), 5.1 (t, 1H, CH), 6.8–7.5 (m, 12H, Ar–H).
3-(naphthalen-3-yl)-4-(3-nitrophenyl)thiazolidin-2-one 5f
Molecular formula C19H14N2O3S; melting point 121–122 °C; yield 60%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.35 (dd, 2H, J = 5.74 Hz, CH2), 5.2 (t, 1H, CH), 6.8–7.6 (m, 9H, Ar–H), 8.1–8.2 (m, 2H, Ar–H).
4-(4-chlorophenyl)-3-(naphthalen-3-yl)thiazolidin-2-one 5g
Molecular formula C19H14ClNOS; melting point 136–137 °C; yield 70%. 1H–NMR (300 MHz, CDCl3, TMS = 0) δ: 3.36 (dd, 2H, J = 5.75, CH2), 5.0 (t, 1H, CH), 6.8–7.6 (m, 11H, Ar–H).