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Synlett 2010(14): 2164-2168  
DOI: 10.1055/s-0030-1258495
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

One-Pot Three-Component Solvent-Free Cyanoaroylation of Aldehydes Using Potassium Hexacyanoferrate(II) as an Environmentally Benign Cyanide Source

Zheng Li*, Guoqiang Tian, Yuanhong Ma
Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, Gansu 730070, P. R. of China
Fax: +86(931)7971989; e-Mail: lizheng@nwnu.edu.cn;
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Publication History

Received 17 March 2010
Publication Date:
16 July 2010 (online)

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Abstract

An efficient method for one-pot three-component solvent-free cyanoaroylation of aldehydes using potassium hexacyanoferrate(II) as an environmentally benign cyanide source and triethylamine as a catalyst has been described. This method has advantages of not using strongly toxic cyanating agents and volatile organic solvents. In addition, the product was obtained in high yield using a simple workup procedure.

Key words

aldehydes - cyanohydrins - green chemistry - multicomponent reaction - nucleophilic addition

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General Procedure: To a 50-mL round-bottomed flask equipped with an air condenser, acyl chloride (15 mmol) and potassium hexacyanoferrate(II) (3 mmol) were added. Then the mixture was heated at 160 ˚C for the time indicated in Table  [²] . After the resulting mixture was cooled to r.t., aldehyde (15 mmol) and Et3N (1.5 mmol) were added. The mixture was further stirred for 5-8 min at r.t. The progress of the reaction was monitored by TLC. After completion of the reaction, CH2Cl2 (20 mL) was added, and the solid was removed by filtration. The filtrate was then washed with icy H2O (3 × 30 mL), and dried with anhyd MgSO4. After removal of the solvent under reduced pressure, the residue was subjected to silica gel flash column chromatography (PE-EtOAc, 20:1) to obtain pure product. The analytical data for the representative products are given below. Cyano(4-methoxyphenyl)methyl Benzoate (Table 2, entry 8): white solid. IR (KBr): 3057, 2250, 1731, 1610, 1514, 1250, 1060, 702 cm-¹. ¹H NMR (400 MHz, CDCl3):
δ = 8.05 (d, J = 6.8 Hz, 2 H), 7.56-7.62 (m, 5 H), 7.25 (d, J = 6.8 Hz, 2 H), 6.65 (s, 1 H), 3.83 (s, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 164.6, 161.1, 133.9, 130.1, 129.6, 128.6, 128.2, 123.9, 116.4, 114.6, 63.1, 55.4. Anal. Calcd for C16H13NO3: C, 71.90; H, 4.90; N, 5.24. Found: C, 71.96; H, 4.88; N, 5.21.

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The analytical data for the isolated representative aroyl cyanide are given below. Benzoyl Cyanide: white solid. IR (KBr): 3073, 2224, 1679, 1594, 1448, 1255, 974, 697 cm-¹. ¹H NMR (400 MHz, CDCl3): δ = 8.13-8.15 (m, 2 H), 7.78-7.82 (m, 1 H), 7.59-7.63 (m, 2 H). ¹³C NMR (100 MHz, CDCl3): δ = 167.8, 136.8, 133.2, 130.4, 129.5, 112.6.