Dalton Transactions PAPER Cite this: Dalton Trans., 2013, 42, 14454 Received 25th June 2013, Accepted 5th August 2013 DOI: 10.1039/c3dt51685g www.rsc.org/dalton Nanocrystalline starch grafted palladium(II) complex for the Mizoroki–Heck reaction† Sanny Verma, a Jean Le Bras, b Suman L. Jain* a and Jacques Muzart b Nanocrystalline starch produced from the acid hydrolysis of gelatinized starch has been used for the first time to support palladium(II) ethylenediamine complex. The nanocrystalline starch supported Pd(II) complex was found to be an efficient and efficiently recycled catalyst for the Mizoroki–Heck reaction of furans and thiophenes with styrenes under mild reaction conditions. Starch is a natural, renewable, and biodegradable polymer pro- duced by many plants as a source of stored energy. 1 It is the second most abundant biomass, which is low cost and indust- rially available. 2 In recent decades, starch nanocrystals (SNCs) have attracted growing interest owing to their nanoscaled size and their renewable and biodegradable nature. Nanocrystalline starches (SNCs) are being used increasingly for various appli- cations in drug delivery systems; 3 however, their uses in cata- lysis are still limited. Palladium catalysis is efficient for various coupling reactions but most procedures used homogeneous systems, 4–8 hence usually the loss of the expensive metals and ligands. Heterogenization of homogeneous metal catalysts is demonstrated to be a superlative approach for combining the advantages of both homogeneous catalysts, i.e. high reactivity and selectivity, and heterogeneous catalysts, such as facile recovery and recyclability. In this regard, a large variety of organic and inorganic matrices have been employed to support Pd-based catalysts to make them recyclable in various coupling reactions. 9 Starch nanocrystals produced from gelati- nized starch via acid hydrolysis have a high affinity for tran- sition metals due to the presence of plenty of hydroxyl functional groups. 10 Recently, Clark et al. developed novel expanded starch based materials having high pore volume, low density and high surface area. 11 These expanded starch materials have been used as support for heterogenizing homo- geneous Pd-catalysts for coupling reactions. 12 However, to the best of our knowledge, there is no literature report on the use of nanocrystalline starch for supporting palladium catalysts. Pd-catalyzed couplings of arenes with alkenes through C–H activation, also called intermolecular Mizoroki–Heck reactions (DMHRs), have gained considerable interest in the recent past. 13 Although a number of effective methods have been reported, the substrate scope is often limited to olefins bearing an electron-withdrawing group as the coupling partner, which limits the applications of these reactions. 14 Among the various arenes used in DMHRs, scanty reports are available on the use of furans and thiophenes. 15 In the present report, we disclose the first successful synthesis of nanocrystal- line starch supported Pd(II)-ethylenediamine complex 16 and its application as a catalyst for the Mizoroki–Heck coupling reaction. Synthesis and characterization of nanocrystalline starch supported Pd complex 6 Nanocrystalline starch was readily synthesized by the acid hydrolysis of native corn starch material by following a literature procedure. 17 The nanocrystalline starch has abundant hydroxyl groups existing in the molecular structure and therefore it can be loaded with a palladium complex through the interaction with hydroxyl groups (Scheme 1). The chemical nature and Scheme 1 Synthesis of nanocrystalline starch supported catalyst 6. † Electronic supplementary information (ESI) available. See DOI: 10.1039/c3dt51685g a Chemical Sciences Division, CSIR-Indian Institute of Petroleum, Dehradun-248005, India. E-mail: suman@iip.res.in; Fax: +91-135-2660202; Tel: +91-135-2525788 b Institut de Chimie Moléculaire de Reims – UMR 7312 CNRS-Université de Reims Champagne-Ardenne UFR des Sciences Exactes et Naturelles, BP 1039, 51687 REIMS, Cedex 2, France 14454 | Dalton Trans., 2013, 42, 14454–14459 This journal is © The Royal Society of Chemistry 2013 Published on 05 August 2013. Downloaded on 09/10/2013 16:06:39. View Article Online View Journal | View Issue