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1 IICT Communication No. 061125.
14
General Procedure.
To the reaction mixture containing substrate 1 (1.0 mmol), CH2Cl2 (10 mL) and alkynone 2 (1.5 mmol) was added a catalytic amount of GaCl3 (0.1 mmol). The resulting mixture was stirred at r.t. for the appropriate time (Table
[1]
). After completion of the reaction as indicated by TLC, EtOAc (20 mL) and H2O (10 mL) were added to the reaction mixture and further stirred at r.t. for additional 10 min. Then, the EtOAc layer was separated and aqueous phase was extracted again with EtOAc (2 × 10 mL). The combined extracts were washed with brine, dried over anhyd Na2SO4 and concentrated in vacuo. The resulting crude product was purified by column chromatography on silica gel (Merck, 60-120 mesh, EtOAc-hexane, 2:8) to afford a pure product.
Spectral Data for Selected Products:
Compound 3a: IR (KBr): νmax = 2924, 2856, 1732, 1556, 1458, 1337, 1234, 1172, 1103, 768, 744, 588 cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.40 (d, J = 16.4 Hz, 1 H), 7.25 (s, 1 H), 7.12-7.05 (m, 1 H), 6.83 (d, J = 8.6 Hz, 1 H), 6.56 (d, J = 16.4 Hz, 1 H), 3.91 (s, 6 H), 2.34 (s, 3 H). MS (EI): m/z (%) = 206 (75) [M+], 191 (100), 163 (15), 149 (18), 107 (20), 77 (18), 43 (70).
Compound 3b: IR (KBr): νmax = 3414, 3136, 2925, 1732, 1629, 1591, 1512, 1412, 1364, 1258, 1115, 1008, 962, 829, 711, 539 cm-1. 1H NMR (300 MHz, CDCl3): δ = 7.41-7.24 (m, 3 H), 6.76 (d, J = 8.3 Hz, 1 H), 6.58 (d, J = 15.8 Hz, 1 H), 5.28 (s, 1 H), 2.38 (s, 3 H), 2.27 (s, 3 H). MS (EI): m/z (%) = 176 (38) [M+], 161 (100), 149 (12), 141 (8), 133 (35), 105 (12), 79 (7), 77 (15), 55 (10), 43 (50).
Compound 3g: IR (KBr): νmax = 3414, 3131, 2929, 1730, 1625, 1512, 1412, 1362, 960 cm-1. 1H NMR (300 MHz, CDCl3): δ = 7.43 (d, J = 16.0 Hz, 1 H), 7.30-7.22 (m, 2 H), 6.74 (d, J = 8.3 Hz, 1 H), 6.55 (d, J = 16.0 Hz, 1 H), 5.78 (s, 1 H), 2.60 (t, J = 7.3 Hz, 2 H), 2.58 (s, 3 H), 1.71-1.62 (m, 2 H), 1.37-1.28 (m, 4 H), 0.91 (t, J = 6.7 Hz, 3 H). MS (EI): m/z (%) = 232 (5) [M+], 176 (25), 161 (100), 133 (25), 105 (10), 77 (30), 43 (60).
Compound 3l: IR (KBr): νmax = 3124, 3002, 2922, 2853, 1663, 1612, 1552, 1474, 1425, 1359, 1254, 1202, 1107, 969, 748, 585 cm-1. 1H NMR (200 MHz, CDCl3): δ = 7.46 (d, J = 1.5 Hz, 1 H), 7.23 (d, J = 15.6 Hz, 1 H), 6.63-6.44 (m, 3 H), 2.30 (s, 3 H). ESI-MS: m/z = 157.1 [M + Na]+, 134.9 [M]+, 121.