Mol Divers DOI 10.1007/s11030-016-9673-z SHORT COMMUNICATION Ethylene glycol promoted catalyst-free pseudo three-component green synthesis of bis(coumarin)s and bis(3-methyl-1-phenyl-1 H - pyrazol-5-ol)s Sushama S. Kauthale 1 · Sunil U. Tekale 2 · Kavita M. Jadhav 1 · Rajendra P. Pawar 1 Received: 11 January 2016 / Accepted: 2 May 2016 © Springer International Publishing Switzerland 2016 Abstract An ethylene glycol promoted catalyst-free practi- cally efficient and sustainable approach has been developed for the synthesis of several benzylidene-bis-(4-hydroxycou- marin)s and 4,4 ′ -(arylmethylene)-bis(3-methyl-1-phenyl-1H- pyrazol-5-ol)s by the pseudo three-component reaction of an aldehyde with 4-hydroxycoumarin and 3-methyl-1-pheny- lpyrazol-5-one, respectively. Inexpensive, non-toxic, and easily available ethylene glycol used as the reaction sol- vent and promoter renders an efficient protocol in terms of catalyst-free reaction conditions, short reaction time, high yield, practical utility, and green approach. Keywords Catalyst-free · Biscoumarins · Bispyrazoles · MCRs · Green chemistry Introduction Considering the increasing environmental pollution and cost of solvents, recently more emphasis has been focused on the development of catalyst-free organic synthesis. Science and technology are being shifted more towards the devel- opment of inexpensive, economic, environmentally benign, and catalyst-free innovative methodologies. Although sol- vents play crucial roles in the development of catalyst-free Electronic supplementary material The online version of this article (doi:10.1007/s11030-016-9673-z) contains supplementary material, which is available to authorized users. B Rajendra P. Pawar rppawar@yahoo.com 1 Department of Chemistry, Deogiri College, Station Road, Aurangabad, MS 431 005, India 2 Department of Chemistry, Shri Muktanand College, Gangapur, MS 431 109, India protocols, many solvents display environmental safety and hazardous challenges. From a green chemistry perspec- tive, when toxic solvents are used for chemical processes it becomes essential to minimize environmental and opera- tional concerns. Coumarin and pyrazole are 2 core structures present in several natural and synthetic molecules that exhibit a wide range of interesting biological activities [1, 2]. Dicoumarol (1) is a naturally occurring anticoagulant of plant and fun- gal origin that functions as vitamin K deplete and reductase enzyme inhibitor [3]. Ethyl biscoumacetate (2) is a vitamin K antagonist [4]. Other important drugs, such as aceno- coumarol, coumatetralyl, and aminocoumarin also contain a coumarin core in their structures. The pyrazole ring appears in the skeleton of many bioac- tive compounds including lonazolac (3), tepoxalin (4), and rimonabant (5) [5] (Fig. 1). Tepoxalin is mainly used to reduce inflammation and as an analgesic to reduce the pain caused by musculoskeletal disorders [6]. Benzylidene-bis-(4-hydroxycoumarin)s are well known for their numerous biological activities including anti- inflammatory [7], antioxidant [8], cytotoxicity [9], antiviral [10], and antimicrobial [11]. Furthermore, pyrazoles and bis- pyrazolones have also been reported as potent insecticides [12], antitumor agents [13], and selective COX-2 inhibitors [14]. The literature is enriched with numerous methods for the synthesis of 3,3 ′ -arylidene bis(4-hydroxycoumarin)s by the condensation of aldehydes and 4-hydroxycoumarin using various catalysts such as tetrabutylammonium bro- mide [15], silica-supported preyssler nanoparticles [16], RuCl 3 · 6H 2 O[17], sodium dodecyl sulfate [18], tetra- butylammonium hexatungstate [19], and aqueous NaCl [20]. The synthesis of 4,4 ′ -(arylmethylene)-bis(3-methyl-1- phenyl-1 H -pyrazol-5-ol)s can be successfully accomplished 123