2349 ISSN 1229-9197 (print version) ISSN 1875-0052 (electronic version) Fibers and Polymers 2015, Vol.16, No.11, 2349-2358 Synthesis, Optical Properties, Dyeing Study of Dihydropyrimidones (DHPMs) Skeleton: Green and Regioselectivity of Novel Biginelli Scaffold from Lawsone Sharad R. Patil, Amol S. Choudhary, Vikas S. Patil, and Nagaiyan Sekar* Tinctorial Chemistry Group, Department of Dyestuff and Intermediate Technology, Department of Dyestuff Technology, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai 400 019, India (Received March 27, 2015; Revised September 24, 2015; Accepted October 21, 2015) Abstract: Ionic liquids have increased popularly in last couple of decades as solvent for its greener approach. Here a novel three-component, one-pot condensation yielding 4-phenyl-3,4-dihydrobenzo[g]quinazoline-2,5,10(1H)-trione is reported in halogen free ionic liquid (HFIL). Components of reaction are aldehyde, urea, and β-keto esters in presence of HFIL N- methyl-2-pyrrolidonium hydrogen sulfate [HNMP] [HSO ] . Comparative reactions were performed under conventional heating and sonication in HFIL. Solvent utility of HFIL makes purification and separation process artless task offering an advantage of five times recyclability without degrading its activity. The use of HFIL is advantageous over conventional solvent due to very short reaction time and halogen-free volatile solvent utility and recyclability. Latterly these compounds applied as disperse dye on polyester and nylon fiber were found to give moderate color and fastness properties. Keywords: Biginelli reaction, Halogen free ionic liquid (HFIL), Lawsone, Regioselective, Ultrasonication, Disperse dye Introduction At the beginning of the new century, it is widely accredited that the development of efficient, practical, and eco-friendly methods of the synthesis has been recognized as one of the most important topics of modern organic synthesis [1,2]. As the biggest pollution crisis in many synthetic organic processes is with toxic and volatile organic solvents. The development of efficient synthetic methodologies for organic reactions in the presence of environmental undeniable alternatives such as ionic liquids (ILs) and ultrasonication is an important challenge [3]. Ultrasound generates the cavitation and collapse of bubbles, which gives massive temperature, pressure, and the bizarre heating and cooling rates (i.e. driving force) [4]. Sonochemistry in ILs is a versatile tool to promote important organic conversion at ambient conditions with enhanced reaction rates [5]. It is due to negligible vapor pressure, which considerably changes the characteristics of cavitation in the bulk [6-9]. There are many reports regarding the use of ionic liquids to overcome the deprivations of traditional molecular solvents so far. The intrinsic worth of ionic liquids are recyclability, non-flammable nature, high thermal stability, non-volatile nature, very low vapour pressure, low toxicity, short reaction time, inbuilt catalytic activity, high chemical stability, high polarity, eco-friendly and good performance in various types of reactions, such as cyclocondensation, trans- esterification, Michael addition reactions, and Prins reaction [10-13]. Typical ionic liquids consist of halogen-containing anions (for example [Cl] - , [PF 6 ] - , [BF 4 ] - , or [AlCl 4 ] - ) which at some extent limits their greenness, due to the liberation of toxic and corrosive HF or HCl into the environment [14-17]. 3,4-Dihydropyrimidinones (DHPMs), a realm of nitrogen containing fused heterocyclic organic compounds, which have diverse therapeutic and prominent biological activities such as anti-tumour, anti-bacterial, anti-viral, anti-inflammatory activities, anti-hypertensive agents, adrenergic antagonists, calcium channel blockers, and other functional properties [18-21]. Due to the wide biological significance of DHPMs, their novel derivatives need to be synthesized by new green methodologies. The DHPM nucleus is synthesised from an aldehyde, urea, and β-keto ester such as ethyl acetoacetate, methyl acetoacetate, acetyl acetone, 1,3-cyclohexanedione, acetophenone [22-25], 3-methyl-1-phenyl-5 (4H)-pyrazolone [26], 1,3-indandione [27], under conventional Biginelli reaction conditions. The novel substituted 4-phenyl-3,4- dihydrobenzo[g] quinazoline-2,5,10 (1H)-trione (new DHPMs scaffold) is synthesized from naturally occurring 2-hydoxy- l,4-naphthoquinone (Lawsone) (3d). This method is not yet reported. The naturally occurring 2-hydoxy-l,4-naphthoquinone acts as a source of active methylene group. 2-Hydoxy-l,4- naphthoquinone is a mono-hydroxyl naphthoquinone [28] pigment extracted from henna plant possessing various biological properties, including anti-tumour activity [29] and dyeing of textile application [30]. The classical synthetic approach towards DHPM nucleus is condensation of β-dicarbonyl compounds, aldehydes and urea or thiourea in presence of acidic condensing agents. The acidity precursors used are HCl/H 2 SO 4 [31,32], H 3 PO 3 /Pd- Cat. [33], PPA-SiO 2 [34], CF 3 COOH/MW [35], montmorillonite KSF [36], zeolites [37], Yb(OTf) 3 [38], Sc(OTf) 3 or La(OTf) 3 [39], cupric chloride [40], zirconium chloride [41], sulfamic acid [42], praseodymium methanesulfonate [43], trichloroacetic acid [44], thiamine hydrochloride [45], 1- methylimidazolium hydrogen sulfate [Hmim]HSO 4 - [46], 1- methyl-3-allylimidazolium hydrogen sulfate [Cmim]HSO 4 - [47], 1-butyl-3-methylimidazolium hydrogen sulfate [Bmim] HSO 4 - [48], [Bmim]FeCl 4 [49], and 1-(2-hydroxyethyl)-3- *Corresponding author: sharad.omd.patil@gmail.com DOI 10.1007/s12221-015-5233-x