- Gram-scale preparation of dialkylideneacetones through Ca(OH)2-catalyzed Claisen-Schmidt condensation in dilute aqueous EtOH
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A synthetic method of dialkylideneacetones has been developed. Compared with known protocols, the method employed catalytic Ca(OH)2 as the cheap, mild base catalyst and dilute aqueous EtOH (20%, v/v) as the green and safe solvent. The procedure was easily operated: In most cases, the product could be isolated by a simple filtration, and purified by washing with water. This paper provided experimental details of the reactions, which could be applied in gram-scale synthesis and should be a very reliable and practical protocol to prepare these useful compounds in laboratory and at the industrial level.
- Zhang, Hao,Han, Mengting,Yang, Chenggen,Yu, Lei,Xu, Qing
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- Alkylation of 6-C(O)R-7-aryl-5-methyl-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidines
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Alkylation of 6-C(O)R-7-aryl-5-methyl-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidines with methyl iodide or ethyl bromide in either saturated aqueous KOH–MeCN or NaH–DMF led to the formation of N4-alkyl derivatives in good yields (60–98%). Reactivity of the acetyl group of N4-alkyl derivatives towards aromatic aldehydes under the conditions of the Claisen–Schmidt reaction was significantly higher than in 4-unsubstituted compounds. The starting 6-C(O)R-7-aryl-5-methyl-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidines were synthesized via a three-component condensation of an aromatic aldehyde, 3-amino-1,2,4-triazole, and a dicarbonyl compound (2,4-pentanedione or ethyl acetoacetate) in DMF.
- Kolosov, Maksim A.,Shvets, Elena H.,Kulyk, Olesia G.,Orlov, Valeriy D.
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p. 1052 - 1056
(2016/08/26)
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- Oxygen as single oxidant for two steps: Base-free one-pot Pd(ii)-catalyzed alcohol oxidation & arylation to halogen-intact β-aryl α,β-enones
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Using oxygen as the sole oxidant for two steps, we developed a new method to synthesize β-aryl α,β-enones by fine-tuning the Pd(ii)-catalyzed oxidation of allyl alcohol to subsequent arylation with arylboronic acids, arylboronic ester and aryltrifluoroborate salt. This one-pot green method does not require copper salt, base, and intermediate isolation. Halogen-bearing chalcones, dibenzylideneacetones and arylalkyl enones were synthesized in good yields. This journal is
- Vellakkaran, Mari,Andappan, Murugaiah M. S.,Nagaiah, Kommu
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p. 45490 - 45494
(2014/12/10)
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- Synthesis of 2-(1,5-diaryl-1,4-pentadien-3-ylidene)- hydrazinecarboximidamide hydrochloride catalyzed by p-dodecylbenzenesulfonic acid in aqueous media under ultrasound irradiation
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Amidinohydrazone compounds are very important synthetic intermediates and can serve as versatile precursors in synthesis of many natural products and drug molecules. The use of ultrasound, p-dodecylbenzenesulfonic acid (DBSA) and water as solvent improved the synthesis of different 2-(1,5-diaryl-1,4- pentadien-3-ylidene)-hydrazinecarboximidamide hydrochlorides. The best reaction conditions for the condensation of 1,5-diphenyl-1,4-pentadien-3-one with aminoguanidine hydrochloride were as follows: 1,5-diphenyl-1,4-pentadiene-3-one (1, 1 mmol), aminoguanidine hydrochloride (1.1 mmol), DBSA (0.5 mmol), water 10 mL, reaction temperature 25-27°C, irradiation frequency 25 kHz. 2a was achieved in 94% yield within 2 h. The other seven amidinohydrazones were obtained in 84-94% yield within 2-3 h under the same conditions. Compared to the method involving catalysis by hydrochloric acid in refluxing EtOH, the advantages of present procedure are milder conditions, shorter reaction times, higher yields, and environmental friendly conditions, which make it a useful strategy for the synthesis of analogues.
- Li, Ji-Tai,Du, Chao,Xu, Xiao-Ya,Chen, Guo-Fen
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experimental part
p. 1033 - 1038
(2012/07/03)
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