Synlett 2005(1): 115-118  
DOI: 10.1055/s-2004-836024
LETTER
© Georg Thieme Verlag Stuttgart · New York

One-Pot Multicomponent Synthesis of β-Acetamido Ketones Based on BiCl3 Generated in situ from the Procatalyst BiOCl and Acetyl Chloride

Rina Ghosh*, Swarupananda Maiti, Arijit Chakraborty
Department of Chemistry, Jadavpur University, Kolkata 700032, India
e-Mail: ghoshrina@yahoo.com;
Further Information

Publication History

Received 21 August 2004
Publication Date:
12 November 2004 (online)

Abstract

Aromatic aldehydes react in one pot at room temperature with enolizable ketones and acetonitrile in the presence of acetyl chloride and catalytic amount of BiOCl producing the corresponding β-acetamido ketones in very high to excellent yields. BiCl3 ­generated in situ from BiOCl and acetyl chloride catalyzes the ­multicomponent reaction.

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General Experimental Procedure: To a solution of aldehyde (1 mmol), enolizable ketone (1 mmol) and BiOCl (20 mol%) in dry MeCN (4 mL) MeCOCl (2 mmol) was added and the reaction mixture was stirred at r.t. After completion of the reaction (checked by TLC, Table [1] ) the mixture was diluted with CH2Cl2 and washed with brine solution (10 mL). The aqueous layer was extracted with CH2Cl2 (3 × 5 mL), the pooled organic layer was then washed subsequently with H2O (1 × 6 mL), NaHCO3 (1 × 6 mL) and finally with H2O (1 × 6 mL). The organic layer was dried over Na2SO4, concentrated and the residue was purified by column filtration on silica gel.

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All products were characterized by NMR, IR spectroscopy and/or elemental analysis and by comparing the physical data with those in the literature. [4] The following spectral data are representative:
Compound 21: White crystals [EtOAc-petroleum ether (60-80 °C)]; mp 130 °C. IR (KBr): 3270, 1675, 1640, 1598, 1570, 1525, 1420, 1365, 1250, 1205, 1170, 1020, 990, 830, 800, 700 cm-1. 1H NMR (300 MHz, CDCl3): δ = 2.00 (s, 3 H), 3.31-3.39 (dd, 1 H, J = 5.95, 16.59 Hz), 3.64-3.71 (dd, 1 H, J = 5.28, 16.57 Hz), 3.84 (s, 3 H), 5.53 (m, 1 H), 6.86 (br s, 1 H), 6.89 (br d, 2 H, J = 8.82 Hz), 7.18-7.34 (m, 5 H), 7.88 (br d, 2 H, J = 8.81 Hz). 13C NMR (75 MHz, CDCl3): δ = 23.37, 42.76, 50.02, 55.46, 113.80, 126.41, 127.30, 128.55, 129.66, 130.45, 141.07, 163.77, 169.49, 197.08. Anal. Calcd for C18H19O3N: C, 72.71; H, 6.44; N, 4.71. Found: C, 72.65; H, 6.82; N, 4.67.
Compound 22: White crystals [EtOAc-petroleum ether (60-80 °C)]; mp 194-195 °C. IR (KBr): 3285, 1685, 1635, 1545, 1525, 1400, 1350, 1310, 1290, 1225, 1200, 755, 735, 700, 690 cm-1. 1H NMR (300 MHz, CDCl3): δ = 3.57-3.64 (dd, 1 H, J = 5.38 Hz, 17.45 Hz), 3.87-3.95 (dd, 1 H, J = 4.94, 17.45 Hz), 5.85 (m, 1 H), 7.44-7.62 (m, 7 H), 7.78 (br d, 1 H, J = 7.8 Hz), 7.84-7.93 (m, 5 H), 8.10 (br d, 1 H, J = 8.11 Hz), 8.28 (s, 1 H). 13C NMR (75 MHz, CDCl3): δ = 42.55, 49.63, 121.39, 122.48, 127.11, 128.16, 128.74, 128.89, 129.64, 131.98, 132.89, 133.67, 134.09, 136.21, 143.47, 166.89, 198.63. Anal. Calcd for C22H18N2O4: C, 70.57; H, 4.84; N, 7.48. Found: C, 70.16; H, 4.96; N, 7.23.