1200
S. ASGHARI AND M. OSIA
aromatic protons), 7.90 (1H, dd, 3JHH = 8.0 Hz and 4JHH = 1.2 Hz, CH); 13C NMR (100.6,
1
CDCl3): δC 28.0 (CMe3), 51.5 (d, JPC = 136.0 Hz, P C), 81.03 (OCMe3), 113.8 (C),
120.1, 122.2 and 124.8 (3CH), 125.0 (d, 1JPC = 95.5 Hz, Cipso), 127.2, and 127.6 (2CH),
3
4
128.7 (d, JPC = 12.8 Hz, Cmeta), 132.6 (CH), 132.7 (d, JPC = 2.9 Hz, Cpara), 133.4(C),
2
134.1 (d, JPC = 10.3 Hz, Cortho), 145.0 and 148.6 (2C), 163.2, and 168.9 (2C O); 31P
NMR (161.97 MHz, CDCl3): δP 13.31; MS, m/z (%): 591 (M+, 2) 561 (M+–NO, 5), 535
(M+ C4H8, 6), 387 [M+–(NO2 C6H4 CH CH + C4H8), 10], 368 [M+–(NO2 C6H4 +
CO2t–Bu), 13], 262 (P+Ph3, 100), 183 [M+–(PPh3 + CO2 + C4H8 + NO2), 52], 108
[M+–(NO2 C6H4–CH CH + PPh3 + C4H9), 34], 77(Ph+, 22), 57 (C4H9+, 18).
General Procedure for Synthesis of Dialkyl 2H-pyran-6-[(E)-2-
(2-Nitrophenyl) Ethenyl]-3,5-Dicarboxylate 5
To a stired solution of 2-nitro trans-cinnamaldehyde (0.35 g, 2 mmol) and alkyl
propiolate 0.34 mL, 4 mmol) was added dropwise a triphenylphosphine (0.52 g, 2 mmol)
in toluene (4 mL) at room temperature. The mixture was refluxed for 8 h. The solvent was
removed under reduced pressure and the residue was purified by silica gel (Merck silica
gel, 230–400 mesh) column chromatography using ethyl acetate: hexane (1:4) as eluent.
The solvent was evaporated under reduced pressure and the products 5a–b were obtained
as yellow powders.
Dimethyl-2H-pyran-6-[(E)-2-(2-Nitrophenyl)Ethenyl]3,5-
Dicarboxylate (5a)
Yellow powder; mp170–172 ◦C; yield 35%; IR (KBr) (νmax, cm−1): 1724 and 1712
1
(C O), 1645 (C C), 1518 and 1338 (NO2); H NMR (400.13 MHz, CDCl3): δH 3.84
3
(3H, s, OCH3), 3.86 (3H, s, OCH3), 5.01 (2H, s, OCH2), 7.54 (1H, t, JHH = 7.5 Hz,
3
3
CH), 7.65 (1H, t, JHH = 7.6 Hz, CH), 7.66 (1H, s, CH), 7.80 (d, JHH = 7.8 Hz, CH),
7.94 and 7.95 (2H, AB quartet, 2JHH = 15.0 Hz, 2CH), 8.08 (1H, d, 3JHH = 8.0 Hz, CH);
13C NMR (100.61 MHz, CDCl3): 51.9 (2OCH3), 65.0 (OCH2), 107.8, and 115.8 (2C),
123.9, 124.9, 129.0, and 129.7 (4CH), 131.5 (C), 132.8, 133.3, and 133.9 (3CH), 147.3 (C),
163.9 (C NO2), 164.6 and 165.3 (2C O); MS, m/z (%): 345 (M+, 6), 269 [M+–(OMe +
Me + NO), 20], 221 [M+–(NO2 + C6H4 + 2H), 30], 184 [M+–(NO2 C6H4 CH CH +
Me) + 2H, 28], 167 [M+–(NO2 C6H4 CH CH + 2CH3), 22], 149[M+–(O2N C6H4 +
CO2Me + Me), 100], 59 (CO2Me+, 35).
Diethyl-2H-pyran-6-[(E)-2-(2-Nitrophenyl)Ethenyl]-3,5-
Dicarboxylate (5b)
Yellow powder, mp 108–110 ◦C; yield 33%, IR (KBr) (νmax, cm−1): 1743 and 1707
(C O), 1648 (C C), 1552 and 1358 (NO2); 1H NMR (400.13 MHz, CDCl3): δH 1.36 (3H,
3
3
3
t, JHH = 7.2 Hz, CH3), 1.39 (3H, t, JHH = 7.2 Hz, CH3), 4.29 (2H, q, JHH = 7.2 Hz,
OCH2), 4.32 (2H, q, 3JHH = 7.2 Hz, OCH2), 4.99 (2H, s, OCH2) 4.5 (1H, td, 3JHH = 7.8 Hz,
4JHH = 1.2 Hz, CH), 7.62–7.66 (2H, m, 2CH), 7.80 (1H, dd, 3JHH = 7.8 Hz, 4JHH = 0.8 Hz,
CH), 7.92 and 7.95 (2H, AB quartet, 2JHH = 15.6 Hz, 2CH), 8.00 (1H, dd, 3JHH = 8.0 Hz,
4JHH = 1.2 Hz, CH); 13C NMR (100.61 MHz, CDCl3): δC 14.3 and 14.4 (2CH3), 60.8,
60.9, and 65.0 (3OCH2), 108.3 and 116.1 (2C), 124.0, 124.8, 129.0, and 129.6 (4CH), 131.6
(C), 132.6, 133.2, and 133.6 (3CH), 148.5 (C), 163.6 (C NO2), 164.3 and 164.9 (2C O).