V. S. Shinu et al. / Tetrahedron Letters 50 (2009) 4838–4843
4843
TM
acetophenone (0.120 mg, 1 mmol), acetyl chloride (0.5 mL), and Selectfluor
(0.018 g, 5 mol % by weight of 2-bromobenzaldehyde) under constant stirring
at room temperature. The reaction was monitored by TLC and was found to be
complete after 4 h. The reaction mixture was then poured into distilled water
and kept for 1 h. The precipitated colorless solid was collected on a filter,
washed with distilled water (3 Â 25 mL), and dried under vacuum. The
vacuum-dried solid was then washed with anhydrous diethyl ether
(2 Â 15 mL) and air dried to yield pure b-acetamido ketone derivative. Mp
156 °C; 1H NMR (300 MHz, CDCl3) d 7.91–7.88 (d, J = 7.38 Hz, 2H), 7.58–7.56 (d,
J = 7.38 and 13.59 Hz, 2H), 7.45–7.41 (t, 3H), 7.1 (s, 3H), 7.08–6.99 (m, 2H),
5.79–5.73 (dd, J = 5.67 and 13.24 Hz, 1H), 3.81–3.73 (dd, J = 5.84 and 16.68 Hz,
1H), 3.48–3.40 (dd, J = 5.37 and 16.68 Hz, 1H), 2.03 (s, 3H); 13C NMR (75 MHz,
CDCl3) d 205.5, 169.7, 133.48, 129.39, 129.22, 128.4, 127.7, 123.91, 50.18, 42.3,
precipitate formed was filtered, washed with water (3 Â 25 mL), and dried
under vacuum. The solid obtained was then washed with anhydrous diethyl
ether (3 Â 15 mL) to yield pure b-acetamido ketone. Mp 190–191 °C; 1H NMR,
(300 MHz, DMSO-d6) d 8.30–8.27 (d, J = 7.85 Hz, 2H), 7.96–7.94 (d, J = 7.40 Hz,
2H), 7.66–7.61 (t, 4H), 7.54–7.49 (t, 2H), 7.29 (s, 4H), 5.35–5.33 (d, J = 5.75 Hz,
2H), 3.56–3.48 (dd, J = 8.6 Hz and 17.20 Hz, 2H), 3.41–3.39 (d, J = 5.52 Hz, 2H),
2.08 (s, 6H); 13C NMR (125 MHz, DMSO-d6) d 197.05, 168.22, 141.55, 136.50,
133.20, 128.69, 127.98, 126.51, 48.56, 44.48, 30.66, 22.59; MS m/z 457 (M+1),
337, 279, 237, 157, 105; FT-IR (KBr) cmax 3251, 1686, 1644, 1596, 1547, 1449,
1408, 1363, 1307, 1266, 1208, 1121, 1094, 1000, 836, 768, 692, 636, 607, 579,
556 cmÀ1
.
15. The mixture obtained from the reactions using aliphatic aldehydes upon
aqueous work-up followed by silica gel chromatography afforded the starting
aldehydes and ketones. The aqueous work-up of the mixture obtained from the
23.43; FT-IR (KBr) cmax 3283.9, 1679.5, 1646.4, 1533.59, 1474, 1401.1, 1361.33,
1256.25, 1228.13, 990.06, 758.01, 691.71, 645.3 cmÀ1; MS m/z 266 (M+1ÀBr),
207, 184, 146, 105, 77, 43.
reaction of a-methylcinnamaldehyde with 4-nitroacetophenone afforded a
product with m/z 222.2 which corresponds to the addition of acetyl chloride to
the aldehyde.
11. The spectral data for the compounds 1a, 1c–e, and 2f–l are reported previously,
see Ref. 8a. The values are well in agreement with the same obtained by the
synthesis of these compounds following the new procedure.
16. Spectral data for 3a: 1H NMR, (400 MHz, CDCl3) d 8.31–8.28 (d, J = 8.88 Hz, 2H),
8.11–8.09 (d, J = 8.88 Hz, 2H), 7.95–7.93 (t, 1H), 7.70–7.68 (d, J = 7.2 Hz, 1H),
7.61–7.58 (t, 1H), 7.45–7.43 (t, 1H), 6.9 (s, 1H), 5.95–5.93 (d, J = 6.4 Hz, 1H),
3.76–3.660(m,, 2H), 2.21–2.17 (t, 2H), 1.59–1.52 (m, 2H), 1.31–1.25 (m, 2H),
0.89–0.86 (t, 3H); 13C NMR (400 MHz,, CDCl3) d 196.63, 172.93, 150.64, 148.40,
140.45, 136.04, 133.684, 129.82, 129.43, 128.75, 125.18, 123.99, 47.32, 43.13,
36.16, 27.50, 22.248, 13.69; MS m/z 402 (M+2), 401; FT-IR (KBr) cmax 3329,
2956, 1689, 1645, 1603, 1521, 1406, 1348, 1236, 1192, 995, 850, 786,
689 cmÀ1. Spectral data for 3b: 1H NMR (400 MHz, DMSO-d6) d 8.54–8.52 (d,
J = 7.2 Hz, 1H), 8.36–8.33 (m, 2H), 8.24–8.21 (m, 2H), 7.95–7.93 (dd, 1H), 7.77–
7.69 (m, 2H), 7.54–7.50 (m, 1H) 5.76–5.71 (m,1H), 3.77–3.70 (dd, J = 10 Hz,
1H), 3.52–3.47 (dd, 1H), 1.76 (s, 3H); 13C NMR (400 MHz, DMSO-d6) d 195.44,
168.73, 150.01, 148.03, 140.80, 138.05, 133.64, 129.49, 128.54, 128.26, 124.07,
123.81, 44.57, 44.83, 22.36; FT-IR (KBr) cmax 3327.21, 3113.11, 1689.64,
1643.35, 1602.85, 1519.91, 1444.68, 1348.24, 1294.24, 1228.66, 1112.93,
995.27, 850.61, 744.52, 709.8, 405.05 cmÀ1; MS m/z 359 (M+2), 358, 299.
Spectral data for 3c: 1H NMR, (400 MHz, CDCl3) d 7.97–7.91 (m, 3H), 7.68–7.66
(d, J = 8.0 Hz, 1H), 7.57–7.54 (m, 1H), 7.40–7.36 (t, 1H), 7.19–7.17 (d, J = 8.8 Hz,
2H), 7.01–7.699 (d, J = 7.2 Hz, 1H), 5.95–5.90 (q, J = 6.8 and 19.2 Hz, 1H), 3.72–
3.57 (m, 2H), 2.63–2.57 (q, 2H), 2.21–2.17(2, 2H) 1.60–1.53 (m, 2H), 1.34–1.26
(m, 5H,), 0.90–0.86 (t, 3H); 13C NMR (400 MHz, CDCl3) d 197.33, 172.57, 172.22,
155.07, 148.41, 136.72, 133.70, 133.45, 129.94, 129.67, 128.39, 125.05, 121.99,
47.31, 42.19, 36.28, 27.75, 27.50, 22.29, 13.72, 8.; MS m/z 428 (M+2), 427; FT-IR
12. Typical experimental procedure for the b-acetamido ketone from
a-substituted
ketones (2m): To a solution of benzaldehyde (0.212 g, 2 mmol), acetyl acetone
(0.200 g, 2 mmol), and acetyl chloride (1 mL) in anhydrous acetonitrile
TM
(25 mL), Selectfluor (0.036 g, 5 mol %) was added and stirred for 2 h at room
temperature (completion of the reaction was monitored by TLC). It was then
poured into crushed ice and the residue obtained was filtered, washed with
water (3 Â 25 mL), and dried under vacuum. The dried residue obtained was
then purified by column chromatography on silica gel with petroleum ether–
ethyl acetate (2:1). The solid obtained was crystallized from ethyl acetate–
petroleum ether (1:2) to yield the b-acetamido ketone. Mp 124–125 °C; 1H
NMR, (300 MHz, CDCl3) d 7.22–7.30 (5H, m), 6.97–6.94 (d, J = 9.21 Hz, 1H),
5.88–5.83 (dd, J = 5.59, 9.36 Hz, 1H), 4.29–4.27 (d, J = 5.43 Hz, 1H), 2.27 (s, 3H),
2.08 (s, 3H), 2.01 (s, 3H); FT-IR (KBr) cmax 3355, 1697, 1643, 1527, 1411, 1365,
1195, 1103, 756, 709, 671, 578, 532, 462 cmÀ1; MS m/z 248 (M+1), 204, 170,
154, 148, 136, 106.
8a
13. The spectral data for the compounds 2f–l are reported previously, see Ref.
.
The values are well in agreement with the same obtained by the synthesis of
these compounds following the new procedure.
14. Typical experimental procedure for the synthesis of b-acetamido ketones from di-
aldehyde (1l): To
a solution of terephthalaldehyde (0.084 g, 0.63 mmol),
acetophenone (0.150 g, 1.26 mmol, two equivalents), and acetyl chloride
TM
(1 mL) in acetonitrile (20 mL), Selectfluor (0.022 g, 0.063 mmol, 5 mol % by
weight of acetophenone) was added and stirred at room temperature for 2 h.
Then the mixture was poured into crushed ice and stirred for 30 min. The
(KBr)
1683.86, 1643.35, 1598.99, 1523.76, 1409.96, 1338.6, 1141.86. 894.97,
742.59 cmÀ1
cmax 3266, 3070.68, 2953.02, 2927.94, 2864.29, 2360.87, 2335.8, 1762.94,
.