%0 Journal Article
%T ¡°On Water¡± Sonochemical Multicomponent Synthesis of Novel Bioactive 1,1¡ä-(Aryl)bis(2-(cyclohexylamino)-2-oxoethane-1,1-diyl) Di(alkanoates and benzoates)
%A Manouchehr Mamaghani
%A Nosrat O. Mahmoodi
%A Farhad Shirini
%A Abbas Azimi-Roshan
%A Azam Monfared
%J Journal of Chemistry
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/125959
%X An expeditious, efficient, and ecofriendly ultrasound-promoted synthesis of a series of novel 1,1¡ä-(aryl)bis(2-(cyclohexylamino)-2-oxoethane-1,1-diyl) di(alkanoate and benzoate) derivatives (6a¨Ck), as useful building block candidates for natural products and drugs, is reported. The target compounds were prepared by the reaction of alkyl or aryl carboxylic acid, various bisaldehydes and isocyanocyclohexane in water using one-pot isocyanide-based multicomponent approach. This efficient protocol without using any catalyst furnished the products in short reaction times (4-5£¿min) and excellent yields (87¨C96%). The antibacterial activity of the selected products was also examined. Some products showed promising activities. 1. Introduction Organic transformations in aqueous solvents are not new to organic chemists; the earliest example dated back to 1882 when Baeyer and Drewsen reported the synthesis of indigo in aqueous acetone [1]. Water possesses many unique physical and chemical properties, and considerable rate acceleration is often observed in reactions carried out under on water conditions over those in organic solvents [2, 3]. These specified properties are the consequence of the unique structure of water [4, 5]. Considerable efforts have been directed at understanding the physical nature of the rate acceleration of water-based reactions. Possible source of rate increase such as hydrophobic hydration offering more favorable environment for the transition state (TS) relative to the reactants enhanced H-bonding in the transition state compared to that in the reactants; high cohesive energy density of water and enforced hydrophobic interactions have been emphasized [6]. The use of water as a solvent for organic transformations offers several ¡°green chemistry¡± benefits [7]. Other advantages of on water reactions include the safety and almost zero cost of water relative to organic solvents and the ease of product isolation. A significant example of an on water accelerated cycloaddition reaction between quadricyclane and dimethyl azodicarboxylate was described by Narayan and coworkers. This reaction took 10£¿min (on water) and 5 days (in toluene) to reach completion [8]. In addition to the rate acceleration or increase in yields, high stereo- and regioselectivity were also obtained for asymmetric aldol reactions and certain Diels-Alder reactions by performing emulsion reactions on water [6]. On the other hand, MCRs are by far the most versatile reactions in terms of scaffolds and number of accessible compounds and have gained prominence with the advent of
%U http://www.hindawi.com/journals/jchem/2013/125959/