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Synlett 2006(15): 2495-2497  
DOI: 10.1055/s-2006-950407
LETTER
© Georg Thieme Verlag Stuttgart · New York

AgI-PEG400-KI Catalyzed Environmentally Benign Synthesis of Aroyl Cyanides Using Potassium Hexacyanoferrate(II) as the Cyanating Agent

Zheng Li*, Shengyi Shi, Jingya Yang
Gansu Key Laboratory of Polymer Materials, 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 31 May 2006
Publication Date:
08 September 2006 (online)

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Abstract

A practical cyanation of aroyl chlorides with 0.2 equivalent of non-toxic cyanide source, K4[Fe(CN)6], 3 mol% AgI, 4 mol% PEG-400, and 3 mol% KI as the catalyst system is described. The reactions were performed in DMF at room temperature and provided the corresponding aroyl cyanides in 64-89% yield, typically in less than ten hours.

Key words

green chemistry - catalysis - synthesis - phase-transfer catalysis - cyanation

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General Procedure: A mixture of AgI (0.1 g, 0.45 mmol), PEG400 (0.24 g, 0.6 mmol), KI (0.08 g, 0.45 mmol), and K4[Fe(CN)6] (1.15 g, 3 mmol) (dried at 80 °C under vacuum for 24 h and finely powdered prior to use) in anhyd DMF (10 mL) was first stirred for 10 min, then aroyl chloride (15 mmol) was added. The mixture was stirred for the appropriate time indicated in Table [2] at r.t. The progress of the reaction was monitored by TLC (PE-EtOAc, 5:1). Then CH2Cl2 (20 mL) was added. The suspension was filtered to remove the solid, the filtrate was washed with cold H2O (3 × 30 mL), and dried over anhyd MgSO4. Then the solvent was removed by distillation and the residue was crystallized from hexane to give the product. 2-Chlorobenzoyl cyanide: IR (KBr): 2089 (C≡N), 1776 cm-1 (C=O). 1H NMR (CDCl3, 400 MHz): δ = 7.29-7.81 (m, 4 H, Ph). Anal. Calcd for C8H4ClNO: C, 58.03; H, 2.44; N, 8.46. Found: C, 57.91; H, 2.50; N, 8.39. 3-Chlorobenzoyl cyanide: IR (KBr): 1964 (C≡N), 1793 cm-1 (C=O). 1H NMR (CDCl3, 400 MHz): δ = 7.22-7.78 (m, 4 H, Ph). Anal. Calcd for C8H4ClNO: C, 58.03; H, 2.44; N, 8.46. Found: C, 58.11; H, 2.49; N, 8.53. 2-Furoyl cyanide: IR (KBr): 2067 (C≡N), 1758 cm-1 (C=O). 1H NMR (CDCl3, 400 MHz): δ = 6.70-7.69 (m, 3 H, Furan). Anal. Calcd. for C6H3NO2: C, 59.51; H, 2.50; N, 11.57. Found: C, 59.70; H, 2.43; N, 11.49. 2-Thiophenecarbonyl cyanide: IR (KBr): 2052 (C≡N), 1766 (C=O). 1H NMR (CDCl3, 400 MHz): δ = 7.10-7.71 (m, 3 H, Thiophene). Anal. Calcd for C6H3NOS: C, 52.54; H, 2.20; N, 11.66. Found: C, 52.42; H, 2.30; N, 11.72.