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Received: 2 November 2014/Accepted: 14 September 2015/Published online: 20 April 2016
© Shiraz University 2016
Abstract Henry reaction is a base-catalyzed reaction which can produce ß-nitroalcohol or nitroethylene derivatives from the condensation of aryl aldehydes and nitromethane under different conditions. In the present article, we introduce hexamethylenetetramine as a basic organocatalyst for Henry reaction, which can produce ßnitroalcohol derivatives from the condensation of aryl aldehydes and nitromethane under different conditions. By application of this organic base, ß-nitroalcohol compounds were produced as the only product in good to excellent yields. In addition, reusability of hexamethylenetetramine in this reaction makes our method green.
Keywords Henry reaction * ß-Nitroalcohol * Organic base * Hexamethylenetetramine * Green synthesis * Reusability * Organocatalyst * Cyclic amine
1Introduction
Notable examples from base-catalyzed reactions which have gained growing attention include aldol by Dalko and Moisan (2004), Knoevenagel (Yadav et al. 2004), Michael (Hara et al. 2006) and Henry reactions (Luzzio 2001).
The Henry reaction (or nitroaldol reaction) discovered (Henry 1895) to be an efficient method for C-C bond construction, the result of the reaction of a nitroalkane with an electrophilic carbonyl derivative (aldehyde or ketone). This reaction became very popular because the resulting ßnitroalcohols are highly valuable synthons for the preparation of useful intermediates in synthetic organic chemistry (Sato et al. 2008; Li et al. 2007; Boruwa and Barua Boruwa and Barua 2006). So their preparation in high yield following a safe and economic procedure is still challenging. Among the large variety of catalysts which are known in this reaction, alkali metal bases and alkaline alkoxides in alcoholic solution (Rosini 1991), Cyclen (Vovard-Le Bray et al. 2010), simple amines (Phukan et al. 2008; Palacios et al. 2005; Gan et al. 2006; Ballini et al. 2003), ammonium salts (Caldarelli et al. 1999), Mn(OAc)2/Schiff base (Zhou et al. 2012), guanidine derivatives (Han et al. 2008; Simoni et al. 2000), organophosphorus derivatives (Wang et al. 2008; Weeden and Chisholm 2006; McNulty et al. 2004), and lithium aluminum hydride (Youn and Kim 2000), cesium fluorides in ionic liquid (Shinde et al. 2010), N,N,N',N'-tetramethylethylenediamine (TMEDA) (Majhi et al. 2009) were used successfully.
Organocatalysts have drawn great attention in recent years, and the reactions promoted by organocatalysts have become an intensively studied area in organic chemistry. Compared...