Journal of the Korean Chemical Society (대한화학회지)

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An Efficient Synthesis of 2,3-Dihydro-2-phenyl-4-quinolones from 2'-Aminoacetophenones

2'-아미노아세토페논으로부터 2,3-다이하이드로-2-페닐-4-퀴놀론의 효과적 합성

  • Lee, Jae-In (Department of Chemistry/Plant Resources Research Institute, Duksung Women's University) ;
  • Jung, Hye-Jin (Department of Chemistry/Plant Resources Research Institute, Duksung Women's University)
  • 이재인 (덕성여자대학교 자연과학대학 화학과/식물자원연구소) ;
  • 정혜진 (덕성여자대학교 자연과학대학 화학과/식물자원연구소)
  • Published : 2007.02.20
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Abstract

Keywords

INTRODUCTION

2,3-Dihydro-2-phenyl-4-quinolones, the aza analogues of flavanones, display various pharmacological activities and also serve valuable precursors to medicinally important 4-quinolones.1 The preparation of 2,3-Dihydro-2-phenyl-4-quinolones is generally accomplished by acid or base catalyzed cyclization of 2'-aminochalcones which are prepared from 2'-aminoacetophenones and benzaldehydes. The treatment of 2'-aminochalcones with orthophosphoric acid in acetic acid,2 sodium ethoxide,3 and sodium hydroxide in ethanol4 leads to the formation of 2,3-Dihydro-2-phenyl-4-quinolones, but these procedures involve the use of an excess of corrosive reagents and strong alkalis, respectively, and furthermore the yields are moderate. 2,3-Dihydro-2-phenyl-4-quinolones can also be prepared by microwave-assisted cyclization of 2'-aminochalcones on montmorillonite K-10 clay5 or silica gel impregnated with indium(Ⅲ) chloride.6 Alternatively, 2,3-Dihydro-2-phenyl-4-quinolones are prepared from the isomerization and subsequent cyclization of 1-(2'-tosylaminophenyl)-3-butene-1-ones with 2 equivalents of DBU7 or acid catalyzed one-pot reaction of anilines and ethyl benzoylacetantes.8 The former, however, proceeds in four steps from nitrobenzaldehydes and some of the latter are of limited synthetic scope due to low yieldS. In this paper we wish to report an efficient synthesis of 2,3-Dihydro-2-phenyl-4-quinolones through the cyclization of 2'-aminochalcones using zinc chloride in high yields.

 

EXPERIMENTAL

Preparation of 1-(2'-aminophenyl)-3-phenyl-2-propene-1-one (3a) . To a solution of 2'-aminocetophenone (540.7 mg, 4.0 mmol) in THF (16 mL) was added sodium methoxide (25 wt.% in CH3OH, 1.0 mL, 4.4 mmol) and benzaldehyde (424.5 mg, 4.0 mmol) at 0℃. The reaction mixture was stirred for 2 h between 0℃ and room temperature. After evaporation of THF, the mixture was poured into sat. NH4Cl (30 mL), extracted with methylene chloride (3×25 mL), and washed with sat. NaHCO3, (30 mL). The combined organic phases were dried over MgSO4, filtered, and concentrated in vacuo. The residue was purified by silica gel column chromatography using 20% EtOAc/n-hexane as an eluant give 3a (840.0 mg, 94%). M.p. 70-71 ℃ (lit.2c 71-72 ℃); 1H NMR (300 MHz, CDCl3) δ 7.86 (dd, J1 =8.3 Hz, J2=1.5 Hz, 1H), 7.74 (d, J=15.6 Hz, 1H), 7.61 (d, J=15.6 Hz, 1H), 7.60-7.64 (m, 2H), 7.37-7.43 (m, 3H), 7.25-7.31 (m, 1H), 6.67-6.72 (m, 2H), 6.33 (s, 2H); FT-IR (KBr) 34.62 & 3334 (NH2), 3021, 1645 (C=O), 1614, 1575, 1448, 1212, 1012, 746, 696 cm-1; Ms m/z (%) 223 (M+, 34), 222 (51), 146 (100), 120 (9), 103 (11), 77 (11).

Preparation of 2,3-dihydro-2-phenyl-4-quinolone (4a) . A solution of 3a (670.0 mg, 3.0 mmol)and zinc chloride (1M in Et2O, 3.3 mL, 3.3 mmol) in acetonitrile (10 mL) was heated to 80 ℃ for 24 h. After evaporation of acetonitrile, the mixture was poured into sat. NH4CI (30 mL) and the aqueous phase was extracted with methylene chloride (3×20 mL). The combined organic phases werer dried over MgSO4, filtered, and evaporated to dryness in vacuo. The residue was recrystallized from 90% n-hexane/EtOAc to give 4a (624.1 mg. 93%) as a pale yellow solid. M.p. 150-151 ℃ (lit.5 148-150 ℃); 1H NMR (300 MHz, CDCl3) δ 7.87 (dd, J1=7.9 Hz, J2=1.5 Hz, 1H), 7.32-7.48 (m, 6H), 6.75-6.81 (m, 1H), 6.69 (d, J=8.3 Hz, 1H), 4.76 (dd, J1=13.4 Hz, J2=4.1 Hz, 1H), 4.51 (s, 1H), 2.90 (dd, J1=16.2 Hz, J2=13.4 Hz, 1H), 2.78 (dd, J1=16.2 Hz, J2=4.1 Hz, 1H); 13C NMR (75 MHz, CDCI3) δ 193.7, 151.9, 141.4, 135.8, 129.4, 128.9, 128.0, 127.0, 119.4, 118.9, 116.3, 58.9, 46.9; FT-IR (KBr) 3330 (N-H), 1655 (C=O), 1608, 1358, 1154, 761, 700 cm-1, Ms m/z (%) 223 (M+, 100), 222 (44), 146 (73), 145 (15), 119 (19), 77 (10).

2,3-Dihydro-2-(2'-methoxyphenyl)-4-quinolone (4b): M.p. 91-92 ℃; 1H NMR (300 MHz, CDCl3) δ 7.85 (dd, J1=7.9 Hz, J2=1.4 Hz, 1H), 7.47 (dd, J1=7.9 Hz, J2=1.5 Hz, 1H), 7.25-7.32 (m, 2H), 6.94-6.99 (m, 1H), 6.89 (d, J=8.3 Hz, 1H), 6.69-6.76 (m, 2H), 5.15 (dd, J1=11.6 Hz, J2=4.6 Hz, 1H), 4.69 (s, 1H), 3.83 (s, 3H), 2.89 (dd, J1=16.2 Hz, J2=4.6 Hz, 1H), 2.79 (dd, J1=16.2 Hz, J2=11.6 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 194.4, 157.0, 152.4, 135.6, 129.5, 129.3, 127.9, 126.9, 121.3, 119.4, 118.4, 116.5, 111.0, 55.8, 51.7, 44.1; FT-IR (KBr) 3335 (N-H), 1660 (C=O), 1607, 1492, 13330, 1242, 1026, 752 cm-1; Ms m/z (%) 253 (M+, 100), 252 (57), 146 (63), 119 (26), 91 (19), 77 (9).

2,3-Dihydro-2-(2'-chlorophenyl)-4-quinolone (4c): M.p. 144-145 ℃ (lit.6 146-147 ℃); 1H NMR (300 MHz, CDCl3) δ 7.85 (d, J=7.9 Hz, 1H), 7.66 (dd, J1=7.4 Hz, J2=1.8 Hz, 1H), 7.25-7.39 (m, 4H), 6.70-6.79 (m, 2H), 5.23 (dd, J1=12.4 Hz, J2=4.1 Hz, 1H), 4.64 (s, 1H), 2.91 (dd, J1=16.3 Hz, J2=4.1 Hz, 1H), 2.73 (dd, J1=16.3 Hz, J2=12.4 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 193.2, 151.9, 138.7, 135.9, 133.2, 130.4, 129.7, 128.0, 127.9, 127.8, 119.5, 119.1, 116.5, 54.6, 44.4; FT-IR (KBr) 3324 (N-H), 3065, 1660 (C=O), 1608, 1482, 1327, 1154, 755 cm-1; Ms m/z (%) 259 (M++2, 34), 257 (M+, 100), 256 (26), 146 (94), 119 (15), 92 (12), 77 (9).

2,3-Dihydro-2-(3'-nitrophenyl)-4-quinolone (4d): M.p. 184-185 ℃ (lit.6 185-186 ℃); 1H NMR (300 MHz, CDCl3) δ 8.40 (dd, J1=1.9 Hz, J2=1.9 Hz, 1H), 8.23 (ddd, J1=8.2 Hz, J2=2.2 Hz, J3=1.1 Hz, 1H), 7.90 (dd, J1=7.9 Hz, J2=1.5 Hz, 1H), 7.80 (d, J=7.7 Hz, 1H), 7.57-7.63 (m, 1H), 7.37-7.42 (m, 1H), 6.83-6.91 (m, 1H), 6.77 (d, J=8.2 Hz, 1H), 4.91 (dd, J1=11.6 Hz, J2=5.5 Hz, 1H), 4.53 (s, 1H), 2.81-2.95 (m, 2H); 13C NMR (75 MHz, CDCl3) δ 192.1, 151.0, 148.6, 143.3, 135.7, 132.8, 130.1, 129.5, 127.6, 123.5, 121.7, 119.1, 116.1, 57.8, 46.2; FT-IR (KBr) 3364 (N-H), 1664 (C=O), 1610, 1529, 1352, 1155, 775 cm-1; Ms m/z (%) 268 (M+, 87), 267 (13), 146 (100), 119 (17), 92 (14), 77 (9).

2,3-Dihydro-2-(4'-methylpheny)-4-quinolone (4e): M.p. 149 ℃ (lit.4 149 ℃); 1H NMR (300 MHz, CDCl3) δ 7.86 (dd, J1=7.9 Hz, J2=1.3 Hz, 1H), 7.34 (d= J=8.0 Hz, 2H), 7.27-7.35 (m, 1H), 7.20 (d= J=8.0 Hz, 2H), 6.74-6.81(m, 1H), 6.70 (d= J=8.3 Hz, 1H), 4.70 (dd, J1=13.6 Hz, J2=3.9 Hz, 1H), 4.52 (s, 1H), 2.86 (dd, J1=16.2 Hz, J2=13.6 Hz, 1H), 2.73 (dd, J1=16.2 Hz, J2=3.9 Hz, 1H), 2.36 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 193.9, 152.0, 138.7, 138.4, 135.8, 130.0, 128.0, 126.9, 119.4, 118.7, 116.3, 58.6, 46.9, 21.6; FT-IR (KBr) 3325 (N-H), 1657 (C=O), 1606, 1507, 1326, 1117, 816, 757 cm-1; Ms m/z (%) 237 (M+, 100), 236 (91), 222 (26), 146 (93), 119 (30), 92 (15).

2,3-Dihydro-2-(4'-methoxyphenyl)-4-quinolone (4f): M.p. 144-145 ℃ (lit.5 146-147 ℃); 1H NMR (300 MHz, CDCl3) δ 7.88 (dd, J1=7.9 Hz, J2=1.5 Hz, 1H), 7.38 (d= J=8.7 Hz, 2H), 7.31-7.36 (m, 1H), 6.93 (d= J=8.7 Hz, 2H), 6.76-6.81 (m, 1H), 6.70 (d= J=8.2 Hz, 1H), 4.71 (dd, J1=13.6 Hz, J2=3.9 Hz, 1H), 4.45 (s, 1H), 3.83 (s, 3H), 2.88 (dd, J1=16.2 Hz, J2=13.6 Hz, 1H), 2.74 (dd, J1=16.2 Hz, J2=3.9 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 193.9, 160.0, 152.0, 135.8, 133.4, 128.2, 128.0, 119.4, 118.8, 116.3, 114.7, 58.3, 55.8, 47.0; FT-IR (KBr) 3331 (N-H), 1655 (C=O), 1608, 1510, 1327, 1251, 1032, 831, 761 cm-1; Ms m/z (%) 253 (M+, 100), 252 (91), 146 (76), 134 (20), 119 (23).

2,3-Dihydro-2-(4'-chloropheny)-4-quinolone (4g): M.p. 169-170 ℃ (lit.5 167-168 ℃); 1H NMR (300 MHz, CDCl3) δ 7.88 (dd, J1=8.0 Hz, J2=1.5 Hz, 1H), 7.34-7.46 (m, 5H), 6.76-6.81 (m, 1H), 6.72 (d= J=8.2 Hz, 1H), 4.75 (dd, J1=12.8 Hz, J2=4.6 Hz, 1H), 4.46 (s, 1H), 2.85 (dd, J1=16.2 Hz, J2=12.8 Hz, 1H), 2.76 (dd, J1=16.2 Hz, J2=4.6 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 193.2, 153.3, 135.9, 134.7, 130.1, 129.6, 128.4, 128.0, 119.8, 119.1, 116.3, 58.3, 46.8; FT-IR (KBr) 3329 (N-H), 1655 (C=O), 1608, 1490, 1327, 1154, 1014, 825, 761 cm-1; Ms m/z (%) 259 (M++2, 34), 257 (M+, 100), 256 (45), 146 (93), 119 (34), 92 (19), 77 (12).

2,3-Dihydro-2-(3'4'-dimethoxyphenyl)-4-quinolone (4h): M.p. 138-139 ℃(lit.5 136-137 ℃); 1H NMR (300 MHz, CDCl3) δ 7.88 (dd, J1=7.9 Hz, J2=1.5 Hz, 1H), 7.32-7.38 (m, 1H), 6.96-7.04(m, 2H), 6.88(d, J=8.3 Hz,1H), 6.76-6.82(m, 1H), 4.49(s,1H), 3.91(s, 3H),3.90(s, 3H),2.89(dd,J1=16.2 Hz, J213.6 Hz, 1H), 2.76(dd,J1=16.2 Hz, J2=3.9 Hz, 1H); 13C NMR(75MHz,CDCI3) δ 193.8, 151.9, 149.7, 149.5, 135.8, 133.9, 128.0, 119.4, 119.3, 118.9, 116.8, 111.6, 109.8, 58.8, 56.4(overlapped OCH3), 47.1; FT-IR (KBr)3341(N-H),3058, 2936, 1663(C=O), 1610, 1516, 1326, 1265, 1027, 760cm-1; Ms m/z(%) 283(M+, 100), 282(72), 266(19), 252(35), 146(75), 105(8).

2,3-Dihydro-2-(3'4'5'-trimethoxyphenyl)-4-quinolone (4i): M.p. 136℃ 1H NMR (300 MHz, CDCl3) δ 7.86(d, J=7.7 Hz, 1H), 7.31-7.37(m, 1H), 6.73-6.82(m, 2H), 6.67(s, 2H), 4.62-4.69(m, 2H), 3.86(overlapped OCH3, s, 9H), 2.71-2.91(m, 2H); 13C NMR (75 MHz, CDCl3) δ193.7, 153.9, 152.0, 138.1, 137.2, 135.8, 128.0, 119.4, 118.9, 116.4, 103.8, 61.2, 59.3, 56.5, 47.1; FT-IR(KBr) 3338 (N-H), 2938, 1663(C=O), 1608, 1503, 1460, 1325, 1235, 1126, 757 cm-1; Ms m/z(%) 313(M+, 100), 312(49), 282(5), 146(52), 120(9).

2,3-Dihydro-7-chloro-2-(2'-methoxyphenyl)-4-quinolone (4j): M.p. 134-135 ℃ 1H NMR (300 MHz, CDCl3) δ 7.76(d, J=8.3 Hz, 1H), 7.40(dd, J1=7.5 Hz, J2=1.4 Hz, 1H), 7.27-7.32(m, 1H), 6.94-6.99(m, 1H), 6.90(d, J=8.2 Hz, 1H), 6.66-6.71(m, 2H), 5.14(dd, J1=10.9 Hz, J2=4.9 Hz, 1H), 4.78(s, 1H), 3.84(s, 3H), 2.90 (dd, J1=16.5 Hz, J2=4.9 Hz, 1H), 2.81 (dd, J1=16.3 Hz, J2=10.9 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 193.2, 157.0, 152.7, 141.7, 129.7, 129.5, 128.7, 126.8, 121.3, 119.1, 117.9, 115.9, 111.0, 55.8, 51.6, 43.6; FT-IR(KBr) 3331 (N-H), 3066, 1662(C=O), 1605, 1493, 1464, 1244, 1086, 752 cm-1; Ms m/z(%) 289 (M++2, 100), 288(39), 287 (M+, 100), 286(71), 182(19), 180(56), 119(17).

2,3-Dihydro-7-chloro-2-(4'-methoxyphenyl)-4-quinolone (4k): M.p. 164 ℃ 1H NMR (300 MHz, CDCl3) δ 7.76(d, J=9.0 Hz, 1H), 7.30(d, J=8.0 Hz, 2H), 7.20(d, J=8.0 Hz, 2H), 6.70-6.77(m, 2H), 4.69(dd, J1=13.3 Hz, J2=4.1 Hz, 1H), 4.63(s, 1H), 2.83(dd, J1=16.3 Hz, J2=4.1 Hz, 1H), 2.71(dd, J1=16.3 Hz, J2=4.1 Hz, 1H), 2.36(s, 3H); 13C NMR (75 MHz, CDCl3) δ 192.9, 152.5, 141.9, 138.9, 137.9, 130.1, 129.5, 126.9, 119.3, 117.8, 115.7, 58.4, 46.5, 21.6; FT-IR(KBr) 3336 (N-H), 1650(C=O), 1611, 1570, 1475, 1261, 1203, 817, 765 cm-1; Ms m/z(%) 273 (M++2, 33), 272(38), 271 (M+, 100), 270(66), 182(23), 180(69), 153(22).

2,3-Dihydro-7-chloro-2-(4'-methoxyphenyl)-4-quinolone (4l): M.p. 157-158 ℃ 1H NMR (300 MHz, CDCl3) δ 7.80(d, J=8.4 Hz, 1H), 7.35(d, J=8.7 Hz, 2H), 6.93(d, J=8.0 Hz, 2H), 6.74(dd, J1=8.4 Hz, J2=1.8 Hz, 1H), 6.71(d, J=1.8Hz, 1H), 4.70(dd, J1=13.3 Hz, J2=4.1 Hz, 1H), 4.51(s, 1H), 3.83(s, 3H), 2.86(dd, J1=16.2 Hz, J2=13.3 Hz, 1H), 2.74(dd, J1=16.2 Hz, J2=4.1 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 192.8, 160.2, 152.4, 141.9, 132.9, 129.6, 128.2, 119.4, 117.9, 115.7, 114.8, 58.1, 55.8, 46.6; FT-IR(KBr) 3327 (N-H), 1648 (C=O), 1610, 1509, 1259, 1206, 1030, 764 cm-1; Ms m/z(%) 289 (M++2, 33), 288(46), 287 (M+, 100), 286(98), 182(25), 180(75), 134(27).

2,3-Dihydro-6,7-dimethoxy-2-phenyl-4-quinolone(4m): M.p. 134 ℃ 1H NMR (300 MHz, CDCl3) δ 7.44-7.49(m, 2H), 7.37-7.44(m, 3H), 7.32(s, 1H), 6.18(s, 1H), 4.72(dd, J1=13.6 Hz, J2=4.2 Hz, 1H), 4.38(s, 1H), 3.88(s, 3H), 3.87(s, 3H), 2.84(dd, J1=16.3 Hz, J2=13.6 Hz, 1H), 2.72(dd, J1=16.3 Hz, J2=4.2 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 192.1, 156.5, 148.7, 143.3, 141.5, 129.3, 128.8, 127.0, 112.0, 108.2, 98.4, 59.6, 56.5, 56.4, 46.4; FT-IR(KBr) 3342 (N-H), 2932, 1646 (C=O), 1617, 1504, 1464, 1360, 1259, 1055, 765, 705 cm-1; Ms m/z(%) 283 (M+, 100), 268(69), 206(18), 164(22), 77(5).

 

RESULTS AND DISCUSSION

2'-Aminochalcones were readily prepared by a modification of Murphy and Wattanasin’s method,9 the aldol condensation of a methanolic solution of actophenones containing solid sodium hydroxide with benzaldehydes. To a solution of 2'-aminoace-tophenones (1) in THF was added methanolic sodium methoxide and benzaldehydes (2) at 0℃. The resulting greenish solution was stirred for 2 h between 0℃ and room tempeature. After usual aqueous workup, the condensed residue was purified by silica gel column chromatography to give 2'-aminochalcones (3) as yellow solids in 76-95% yields(Scheme 1). The reaction proceeded well regardless of the kind of substituents(chloro, methoxy, methyl, and nitro) on both 2'-aminoactophenones and benzaldehydes.

The cyclization of 3 proceeded by the intramolec-ular conjugate addition of the amino group to the a,β-unsaturated carbonyl group of 3. To find out optimum conditions of the cyclization of 3, the effect of metal salts and solvents was briefly examined for the cyclization of 1-(2'-aminophenyl)-3-phenyl-2-propene-1-one(3a). The reaction of 3a with 1 equiv of zinc chloride in acetonitrile, THF, and 1,2-dichloroethane at reflux temperature gave 2,3-dihy-dro-2-phenyl-4-quinolone (4a) in 91%, 23%, and 17% yield, respectively, after 24h. The reaction of 3a with tin(Ⅱ) chloride and zirconium(Ⅳ) chloride in acetonitrile gave 4a in 78%and 50% yield, respectively. Thus, the intramolecular cyclization of 3 was carried out using zinc chloride in acetonitrile at 80 ℃. This cyclization seems to procced by the intramolecular 1,4-addition of amino group to the activated a,β-unsanturated carbonyl group of 3 by zinc chloride, followed by subsequent elimination of hydrogen chloride from the resulting cyclic intermediate. After complection of the reaction, the mixture was poured into sat. NH4CI, extracted wih methylene chloride, and the condensed residue was recrystal-lized in 90% n-hexane/EtOAc to give 4 as pale yellow solids in high yields(76-93%).

As shown in Table 1, various 2,3-dihydro-2-phenyl-4-quinolones were synthesized in overall high yields (62-89%) by this method. The reaction worked well for the chloro (4j-4l) and methoxy substituent (4m) on the A-ring of 4. Also, the reaction worked well for the chloro (4c, 4g), nitro (4d), methyl (4e, 4k), and methoxy substituents (4f, 4h, 4i, 4l) on the B-ring of 4 regardless of the properties and the position of substituents under the reaction conditions described. In summary, the present method provides an efficient synthesis of 4 from 1 with regard to (ⅰ) operational simplicity(ⅱ) high yields, and(ⅲ) generlapplicability containing various substituents on both rings and, therefore, it may be utilized as a practicl alternative to the previous methods.

Scheme 1.

Table 1.aOverall yields of two steps from the starting 2'-aminoacetophenones.

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