Mohammad Saeed ABAEE, Somayeh CHERAGHI

9242

Aqueous DABCO, an efficient medium for rapid organocatalyzed Knoevenagel condensation and the Gewald reaction

In the presence of water and 1,4-diazabicyclo[2.2.2]octane, several aldehydes and cyclic ketones underwent efficient Knoevenagel condensation with malononitrile and ethyl cyanoacetate to produce the respective a.b-unsaturated systems within fairly short time periods. As a result, high yields of conjugated products were easily obtained. Products could be engaged in a Gewald reaction, either stepwise or in situ, to produce efficiently their respective 2-aminothiophenes within 4--7 h.

Anahtar Kelimeler:

Knoevenagel condensation, Gewald reaction, organocatalysis, aqueous conditions, amine

Aqueous DABCO, an efficient medium for rapid organocatalyzed Knoevenagel condensation and the Gewald reaction

In the presence of water and 1,4-diazabicyclo[2.2.2]octane, several aldehydes and cyclic ketones underwent efficient Knoevenagel condensation with malononitrile and ethyl cyanoacetate to produce the respective a.b-unsaturated systems within fairly short time periods. As a result, high yields of conjugated products were easily obtained. Products could be engaged in a Gewald reaction, either stepwise or in situ, to produce efficiently their respective 2-aminothiophenes within 4--7 h.

Keywords:

Knoevenagel condensation, Gewald reaction, organocatalysis, aqueous conditions, amine,

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CDCl3) δ 7.85 (d, J = 7.5 Hz, 2H), 8.35 (d, J = 7.5 Hz, 2H), 8.79 (s, 1H); IR (KBr disk) ν 2220, 1600 cm −1 ;
N2O2(Mw 202.21): C, 65.34; H, 4.98; N, 13.85. Found: C, 65.54; H, 5.09; N, 13.78%. 2-(Thiophen-2-ylmethylene)malononitrile (6m). Brown crystals, mp 96–98 ◦ C;1H NMR (500 MHz, CDCl3) δ 7.26–7.30 (m, 1H), 7.83–7.86 (m, 1H), 7.88–7.90 (m, 2H) ppm; IR (KBr) ν 2225, 1575, 735 cm −1 ;

Turkish Journal of Chemistry-Cover

ISSN: 1300-0527
Yayın Aralığı: Yılda 6 Sayı
Yayıncı: TÜBİTAK

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