H.S.P.Rao et al./ Tetrahedron 58 (2002) 2189±2199
2195
742, 690, 655 cm21; dH (200 MHz, CDCl3) 7.89±7.94 (2H,
m), 7.35±7.55 (3H, m), 3.03±3.11 (2H, m), 1.90±2.33 (6H,
m), 1.68±1.89 (2H, m), 1.56±1.65 (1H, m); dC (50 MHz,
CDCl3) 220.63, 199.75, 136.88, 132.95, 128.54, 128.01,
48.13, 38.01, 36.13, 29.84, 24.27, 20.60.
4.4.1. 1-(4-Bromophenyl)-3-(2-oxocyclopentyl)-1-propa-
none (10). Yield 529 mg (48%); mp 678C; Rf (90:10 hexane/
ethyl acetate) 0.44; nmax (Nujol) 3079, 2958, 2878, 1944,
1736, 1676, 1488, 1454, 1407, 1266, 1158, 984, 829, 776,
574, 500 cm21; dH (400 MHz, CDCl3) 7.83(2H, dd, J4.9,
2.0 Hz), 7.59 (2H, dd, J4.9, 2.0 Hz), 3.02±3.16 (2H, dm,
J6.8 Hz), 1.98±2.35 (6H, m), 1.77±1.86 (2H, m), 1.57
(1H, ddd, J17.0, 10.0, 7.0 Hz); dC (100 MHz, CDCl3)
220.62, 198.53, 135.30, 131.66, 129.39, 127.91, 47.84,
37.88, 35.88, 29.68, 23.93, 20.42.
4.2.2. trans-2,5-Di-(3-oxo-3-phenylpropyl)-1-cyclopenta-
none (4a). Yield 555 mg (7%); Rf (90:10 hexane/ethyl
acetate) 0.18; nmax (KBr) 2900, 2820, 1710, 1660, 1430,
1350, 1240, 1140, 980, 730, 670 cm21; dH (400 MHz,
CDCl3) 7.96 (4H, d, J8.3Hz), 7.42±7.56 (6H, m), 3.09±
3.13 (4H, m), 2.10±2.22 (4H, m), 1.82±1.85 (4H, m), 1.45±
1.46 (2H, m); dC (100 MHz, CDCl3) 221.76, 200.05,
137.04, 133.31, 128.85, 128.30, 48.70, 36.31, 28.07,
24.93; LRMS: 348 (M1, 0.6), 331 (5), 229 (11), 228 (54),
210 (10), 133 (9), 121 (6), 109 (12), 105 (100), 95 (12), 77
(75), 76 (26), 55 (16), 51 (18%); elemental analysis calcd
for C23H24O3: C, 79.28; H, 6.94. Found: C, 79.11; H, 6.91.
4.4.2. Mixture of cis- and trans-2,5-di[3-(4-bromo-
phenyl)-3-oxopropyl]cyclopentan-1-one (14). Yield
76 mg (8%); Rf (90:10 hexane/ethyl acetate) 0.23; nmax
(Nujol) 2960, 1726, 1680, 1587, 1480, 1462, 1378, 1250,
1210, 1158, 1093, 823, 769, 565 cm21; dH (400 MHz,
CDCl3): d 7.83(4H, dd, J6.8, 2.0 Hz), 7.59 (4H, dd,
J6.3, 2.0 Hz), 3.03±3.15 (4H, m), 1.98±2.30 (4H, m),
1.70±1.88 (4H, m), 1.45±1.49 (2H, m); dC (100 MHz,
CDCl3) 221.82 (2CO), 199.00, 198.95, 135.74 (2C),
132.17 (4C), 129.87 (4C), 128.50 (2C), 48.58, 47.49,
36.37, 36.26, 28.11, 27.58, 25.03, 24.84; LRMS: M1 peak
did not appear, 306 (70), 308 (72), 198 (31), 200 (29), 183
(100), 185 (99), 182 (47), 184 (53), 155 (50), 157 (51), 154
(25), 156 (39), 131 (13), 76 (63), 55 (66%); elemental
analysis calcd for C23H22Br2O3: C, 54.57; H, 4.38. Found:
C, 54.39; H, 4.39.
4.3. Reaction of N,N-dimethylamino-4-chloropropio-
phenone (5) with cyclopentanone (2)
Following the general procedure described above, the
reaction of Mannich base 5 (1.62 g, 7.7 mmol) and cyclo-
pentanone 2 (1.94 g, 23mmol) furnished a mixture of
diketone 9 and triketone 13 which were puri®ed by column
chromatography.
4.3.1. 1-(4-Chlorophenyl)-3-(2-oxocyclopentyl)-1-propa-
none (9). Yield 1.38 g (72%); mp 1158C; Rf (90:10 hexane/
ethyl acetate) 0.46; nmax (Nujol) 2962, 1734, 1676, 1587,
1452, 1406, 1371, 1255, 1217, 1153, 1093, 1014, 979, 827,
769, 569, 491 cm21; dH (200 MHz, CDCl3) 7.90 (2H, dd,
J4.3, 1.9 Hz), 7.36 (2H, dd, J7.3, 1.9 Hz), 3.09 (2H, ddd,
J10.8, 6.9, 1.9 Hz), 2.00±2.31 (6H, m), 1.77±1.87 (2H,
m), 1.61±1.64 (1H, m); dC (50 MHz, CDCl3): d 220.45,
198.51, 139.42, 135.30, 129.48, 128.87, 48.05, 38.03,
36.10, 29.93, 24.33, 20.58.
4.5. Reaction of N,N-dimethylamino-4-methylpropio-
phenone (7) with cyclopentanone (2)
Following the general procedure described above, the
reaction of Mannich base 7 (1.67 g, 8.8 mmol) and cyclo-
pentanone 2 (2.21 g, 26.3mmol) furnished a mixture of
diketone 11 and triketone 15 which were puri®ed by column
chromatography.
4.5.1. 1-(4-Methylphenyl)-3-(2-oxocyclopentyl)-1-propa-
none (11). Yield 1.31 g (65%); mp 718C; Rf (90:10 hexane/
ethyl acetate) 0.41; nmax (Nujol) 2958, 2878, 1729, 1676,
1608, 1454, 1373, 1259, 1219, 1158, 984, 829, 769, 567,
494, 467, 420 cm21; dH (300 MHz, CDCl3) 7.86 (2H, d,
J9.5 Hz), 7.25 (2H, d, J10.9 Hz), 3.08 (2H, ddd,
J9.0, 6.3, 3.0 Hz), 2.4 (3H, s, CH3), 2.00±2.30 (6H, m),
1.75±1.83(2H, m), 1.54±1.59 (1H, m); dC (75 MHz,
CDCl3) 220.91, 199.54, 143.79, 134.40, 129.70, 128.20,
48.24, 38.10, 36.07, 29.90, 24.39, 21.61, 20.66.
4.3.2. Mixture of cis- and trans-2,5-di[3-(4-chloro-
phenyl)-3-oxopropyl]cyclopentan-1-one (13). Yield
144 mg (9%); Rf (90:10 hexane/ethyl acetate) 0.21; nmax
(Nujol) 2961, 1724, 1684, 1589, 1487, 1452, 1400, 1367,
1309, 1255, 1203, 1155, 1093, 987, 831, 769, 565,
518 cm21; dH (200 MHz, CDCl3) 7.90 (4H, d, J8.3Hz),
7.43(4H, d, J8.0 Hz), 3.10 (4H, t, J8.3Hz), 2.05±2.22
(4H, m), 1.70±1.95 (4H, m), 1.47±1.60 (2H, m); dC
(50 MHz, CDCl3) 221.49 (2CO), 198.50 (2CO), 139.46
(2C), 135.07 (2C), 129.46 (4C), 128.88 (4C), 48.29,
47.20, 36.10, 35.97, 27.81, 27.28, 24.76, 24.58; LRMS:
415 (M1, 4), 417 (2.5), 262 (46), 264 (15), 154 (38), 156
(12), 139 (100), 141 (34), 111 (44), 113 (14), 56 (40%);
elemental analysis calcd for C23H22Cl2O3: C, 66.19; H,
5.31. Found: C, 65.75; H, 5.31.
4.5.2. Mixture of cis- and trans-2,5-di[3-(4-methyl-
phenyl)-3-oxopropyl]cyclopentan-1-one (15). Yield
164 mg (10%); Rf (90:10 hexane/ethyl acetate) 0.19; nmax
(Nujol) 2958, 2911, 2871, 1729, 1682, 1608, 1373, 1306,
1232, 1185, 984, 823, 782, 567, 460 cm21; dH (300 MHz,
CDCl3) 7.86 (4H, d, J5.2 Hz), 7.25 (4H, d, J4.7 Hz),
3.08 (4H, ddd, J5.0, 3.0, 1.8 Hz), 2.40 (6H, s, CH3),
2.00±2.33 (4H, m), 1.81±1.86 (4H, m), 1.69±1.76 (2H,
m); dC (75 MHz, CDCl3) 221.54 (2CO), 199.49, 199.42,
143.77 (2C), 134.32 (2C), 129.24 (4C), 128.17 (4C),
48.48, 47.37, 36.07, 35.93, 27.79, 27.22, 24.96, 24.76,
21.61 (2C); LRMS: 376 (M1, 0.8), 358 (6), 243 (11), 242
(48), 147 (12), 135 (11), 134 (59), 119 (100), 96 (11), 91
(68), 65 (23), 55 (17%); elemental analysis calcd for
C23H28O3: C, 79.75; H, 7.50. Found: C, 79.66; H, 7.47.
4.4. Reaction of N,N-dimethylamino-4-bromopropio-
phenone (6) with cyclopentanone (2)
Following the general procedure described above, the
reaction of Mannich base 6 (955 mg, 3.8 mmol) and cyclo-
pentanone 2 (941 mg, 11.2 mmol) furnished a mixture of
diketone 10 and triketone 14 which were puri®ed by column
chromatography.