RESEARCH FRONT
Synthesis of 2,3-Dihydro-4(1H)-quinolones
467
8-Methoxy-2,3-dihydroquinolin-4(1H)-one (2j)
as a yellow, crystalline solid, mp 127–1298C (lit.[16] mp 122–
1238C) (Found: Mþꢂ, 181.0292. C9H835ClNO requires Mþꢂ
,
Subjection of N-arylazetidin-2-one 1j to the reaction condi-
tions specified in the general procedure afforded, after work-up,
flash chromatography, and concentration of the appropriate
fractions (RF 0.2 in 1/1 v/v ethyl acetate/hexane), the title
181.0294). dH (300 MHz, CDCl3) 7.10 (t, J 8.3, 1H), 6.71 (dd, J
8.3 and 1.2, 1H), 6.55 (dd, J 8.3 and 1.1, 1H), 4.56 (br s, 1H),
3.57 (t, J 7.1, 2H), 2.73 (t, J 7.1, 2H). dC (75 MHz, CDCl3) 191.9,
153.7, 134.8, 133.9, 120.6, 115.6, 114.7, 41.4, 39.0. nmax (KBr)
3351, 2921, 2851, 1650, 1603, 1565, 1514, 1453, 1423, 1344,
compound 2j[35] (95%) as a yellow oil (Found: Mþꢂ
,
177.0790. C10H11NO2 requires Mþꢂ, 177.0790). dH (300 MHz,
CDCl3) 7.48–7.45 (complex m, 1H), 6.84 (dd, J 8.1 and 1.2, 1H),
6.66 (t, J 8.1, 1H), 4.95 (br s, 1H), 3.87 (s, 3H), 3.60 (t, J 7.1, 2H),
2.70 (t, J 7.1, 2H). dC (75 MHz, CDCl3) 193.2, 146.6, 142.9,
118.4, 118.1, 115.7, 113.0, 55.2, 41.5, 37.4. nmax (KBr) 3390,
1667, 1614, 1583, 1505, 1452, 1371, 1346, 1295, 1242, 1180,
1236, 1162, 1036, 777 cmꢀ1. m/z (EI, 70 eV) 183 and 181 (Mþꢂ
,
35 and 100%), 155 and 153 (24 and 73), 126 (49), 69 (52).
7-Nitro-2,3-dihydroquinolin-4(1H)-one [2n(a)] and
5-Nitro-2,3-dihydroquinolin-4(1H)-one [2n(b)]
1067, 1044, 865, 785, 738 cmꢀ1. m/z (EI, 70 eV) 177 (Mþꢂ
92%), 162 (100), 134 (36), 106 (42).
,
Subjection of N-arylazetidin-2-one 1n to the reaction condi-
tions specified in the general procedure afforded, after work-up
and flash chromatography, two fractions, A and B.
7-Methoxy-2,3-dihydroquinolin-4(1H)-one [2l(a)] and
5-Methoxy-2,3-dihydro-quinolin-4(1H)-one [2l(b)]
Concentration of fraction A (RF 0.3 in 1/1 v/v ethyl acetate/
hexane), afforded the title compound 2n(a)[23] (5%) as a red,
crystalline solid, mp 2208C (lit.[23] mp 229–232.78C) (Found:
Subjection of N-arylazetidin-2-one 1l to the reaction condi-
tions specified in the general procedure afforded, after work-up
and flash chromatography, two fractions, A and B.
M
þꢂ, 192.0535. C9H8N2O3 requires Mþꢂ, 192.0535). dH
(300 MHz, (D6)DMSO) 7.77 (d, J 8.7, 1H), 7.62 (d, J 2.4,
1H), 7.43 (br s, 1H), 7.28 (dd, J 8.7 and 2.4, 1H), 3.55–3.50
(complex m, 2H), 2.62 (t, J 7.2, 2H). dC (75 MHz, (D6)DMSO)
192.6, 152.8, 151.5, 128.7, 121.0, 110.9, 109.3, 40.4, 36.9. nmax
(KBr) 3342, 2923, 2853, 1661, 1622, 1521, 1419, 1371, 1348,
1262, 1240, 1174, 1118, 1038, 879, 810, 731 cmꢀ1. m/z (EI,
70 eV) 192 (Mþꢂ, 100%), 146 (37), 118 (55).
Concentration of fraction A (RF 0.2 in 1/1 v/v ethyl acetate/
hexane) afforded the title compound 2l(a)[16] (65%) as a beige,
crystalline solid, mp 139–1408C (lit.[16] mp 138–1398C) (Found:
M
þꢂ, 177.0790. C10H11NO2 requires Mþꢂ, 177.0790). dH
(300 MHz, CDCl3) 7.81 (d, J 8.7, 1H), 6.33 (dd, J 8.7 and 2.4,
1H), 6.08 (d, J 2.4, 1H), 4.40 (br s, 1H), 3.80 (s, 3H), 3.56 (t, J
7.1, 2H), 2.65 (t, J 7.1, 2H). dC (75 MHz, CDCl3) 192.4, 165.2,
153.9, 129.7, 113.7, 106.7, 98.0, 55.3, 42.3, 37.7. nmax (KBr)
3339, 1638, 1612, 1576, 1525, 1494, 1418, 1345, 1250, 1226,
1214, 1185, 1172, 1114, 1054, 1018, 816, 796 cmꢀ1. m/z (EI,
70 eV) 177 (Mþꢂ, 100%), 149 (74), 122 (35).
Concentration of fraction B (RF 0.1 in 1/1 v/v ethyl acetate/
hexane), afforded the title compound 2n(b) (19%) as a yellow,
crystalline solid, mp 1808C (with decomposition) (Found: Mþꢂ
,
192.0535. C9H8N2O3 requires Mþꢂ, 192.0535). dH (300MHz,
(D6)DMSO) 7.55 (br s, 1H), 7.36 (dd, J 8.4 and 7.2, 1H), 6.96–
6.93 (complex m, 1H), 6.71 (complex m, 1H), 3.51–3.46 (com-
plex m, 2H), 2.57 (t, J 7.4, 2H). dC (75 MHz, (D6)DMSO) 190.1,
153.6, 149.9, 134.6, 118.9, 109.9, 107.0, 36.9 (one signal
obscured or overlapping). nmax (KBr) 3354, 1662, 1619, 1531,
1438, 1370, 1347, 1319, 1238, 1170, 1083, 1036, 866, 821, 802,
742 cmꢀ1. m/z (EI, 70eV) 192 (Mþꢂ, 100%), 118 (76), 91 (54).
Concentration of fraction B (RF 0.1 in 1/1 v/v ethyl acetate/
hexane) afforded the title compound 2l(b)[16] (32%) as a yellow,
crystalline solid, mp 183–1848C (lit.[16] mp 183–1848C) (Found:
M
þꢂ, 177.0790. C10H11NO2 requires Mþꢂ, 177.0790). dH
(300 MHz, CDCl3) 7.17 (t, J 8.3, 1H), 6.22 (t, J 8.3, 2H), 4.47
(br s, 1H), 3.87 (s, 3H), 3.55–3.50 (complex m, 2H), 2.67 (t, J
7.1, 2H). dC (75 MHz, CDCl3) 192.6, 161.3, 154.0, 135.1, 109.2,
108.1, 99.6, 55.7, 41.6, 39.5. nmax (KBr) 3296, 1644, 1607, 1580,
1526, 1456, 1448, 1423, 1360, 1345, 1263, 1232, 1169, 1129,
1110, 1078, 1039, 971, 792 cmꢀ1. m/z (EI, 70 eV) 177 (Mþꢂ
100%), 149 (48), 148 (59), 122 (42), 107 (41).
General Procedure for Preparing 3-Phenyl-2,3-dihydro-
4(1H)-quinolones 2o–u
,
The title compounds were prepared by triflic acid promoted
rearrangement of the corresponding N-aryl-2-phenyl-azetidin-
2-ones 1o–u under the same conditions as employed for the
conversions 1a–n - 2a–n described above. The crude products
were purified by flash chromatography (silica) to give, after
concentration of the appropriate fractions, the relevant
3-phenyl-2,3-dihydro-4(1H)-quinolones 2o–u.
7-Chloro-2,3-dihydroquinolin-4(1H)-one [2m(a)] and
5-Chloro-2,3-dihydro-quinolin-4(1H)-one [2m(b)]
Subjection of N-arylazetidin-2-one 1n to the reaction condi-
tions specified in the general procedure afforded, after work-up
and flash chromatography, two fractions, A and B.
3-Phenyl-2,3-dihydroquinolin-4(1H)-one (2o)
Concentration of fraction A [RF 0.2(1) in 1/2 v/v ethyl
acetate/hexane] afforded the title compound 2m(a)[16] (51%)
as a yellow, crystalline solid, mp 129–1308C (lit.[16] mp 128–
Subjection of N-aryl-2-phenylazetidin-2-one 1o to the reac-
tion conditions specified in the general procedure afforded, after
work-up, flash chromatography, and concentration of the appro-
priate fractions (RF 0.2 in 1/5 v/v ethyl acetate/hexane), the title
compound 2o (86%) as a yellow solid, mp 138–1408C (Found:
1308C) (Found: Mþꢂ, 181.0293. C9H835ClNO requires Mþꢂ
,
181.0294). dH (300 MHz, CDCl3) 7.77 (d, J 8.1, 1H), 6.71–6.67
(complexm, 2H), 4.44 (brs, 1H), 3.61–3.56(complex m, 2H), 2.69
(t, J 7.1, 2H). dC (75 MHz, CDCl3) 192.7, 152.4, 141.2, 129.2,
118.4, 117.7, 115.1, 42.0, 37.7. nmax (KBr) 3358, 2923, 2853,
1677, 1648, 1604, 1569, 1509, 1457, 1404, 1391, 1365, 1321,
1257, 1239, 1214, 1172, 1119, 1084, 1069, 1039, 873, 848,
785 cmꢀ1. m/z (EI, 70 eV) 183 and 181 (Mþꢂ, 34 and 100%),
182 and 180 (30 and 55), 155 and 153 (22 and 64), 126 (40).
Concentration of fraction B [RF 0.2(4) in 1/2 v/v ethyl
acetate/hexane] afforded the title compound 2m(b)[16] (46%)
M
þꢂ, 223.0997. C15H13NO requires Mþꢂ, 223.0997). dH
(300 MHz, (D6)DMSO) 7.64 (dd, J 8.1 and 1.8, 1H), 7.34–
7.22 (complex m, 6H), 7.03 (br s, 1H), 6.79 (d, J 7.5, 1H), 6.62
(m, 1H), 3.80 (dd, J 9.5 and 6.5, 1H), 3.70–3.54 (complex m,
2H). dC (75 MHz, (D6)DMSO) 193.2, 152.6, 138.2, 135.0,
128.7, 128.4, 127.2, 126.9, 117.9, 116.2, 116.1, 51.4, 46.8. nmax
(KBr) 3402, 1666, 1613, 1573, 1502, 1481, 1461, 1450, 1429,
1370, 1340, 1235, 1191, 1162, 1146, 1112, 1097, 1073, 1020,