Journal of Molecular Catalysis A: Chemical 276 (2007) 34–40 Heterogeneous hydrogenation of bicyclo[2.2.2]octenes on Rh/TPPTS/LDH catalysts Florentina Iosif a , Vasile I. Parvulescu a,∗ , M. Elena P´ erez-Bernal b , Ricardo J. Ruano-Casero b , Vicente Rives b,∗∗ , Kriˇ stof Kranjc c , Slovenko Polanc c , Marijan Koˇ cevar c,∗∗∗ , Emilie Genin d , Jean-Pierre Genˆ et d , V´ eronique Michelet d,∗ ∗ ∗∗ a University of Bucharest, Department of Chemical Technology and Catalysis, B-dul Regina Elisabeta 4-12, Bucharest 030016, Romania b Universidad de Salamanca, Departamento de Quimica Inorganica, Plaza de los Ca¨ ıdos, s/n 37008, Salamanca, Spain c Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aˇ skerˇ ceva 5, SI-1000 Ljubljana, Slovenia d Laboratoire de Synth` ese S´ elective Organique et Produits Naturels, ENSCP, UMR 7573, 11 rue P. et M. Curie, F-75231 Paris Cedex 05, France Received 14 May 2007; received in revised form 15 June 2007; accepted 18 June 2007 Available online 22 June 2007 Abstract The Rh-TPPTS complex was heterogenized onto layered double hydroxides (LDH) Zn 3 AlCl and Co 2 FeCO 3 using ion-exchange procedure. Before ion exchange, the Rh precursor [Rh(cod)Cl] 2 was dissolved together with the TPPTS ligand in deionised water and stirred for 12 h. After stirring, the LDH was added to the solution and stirred for another 24h, then filtered, washed with deionised water, and dried under vacuum at room temperature for 16 h. The characterization of the catalysts was carried out using several techniques: ICP-AES, N 2 adsorption–desorption isotherms at -196 ◦ C, thermal analysis, powder X-ray diffraction, XPS and DRIFTs. Substrates were prepared via Diels–Alder reaction of various 2H-pyran-2-ones with N-substituted maleimides in an aqueous medium with microwave irradiation. The catalytic tests were performed in a stirred stainless-steel autoclave using H 2 pressures in the range 20–40 atm, 30 mg catalyst and 30 mg substrate, at different temperatures. Hydrogenation of bicyclo[2.2.2]octenes showed that these strained and functionalized cycloadducts were inert to classic catalysts but could be hydrogenated by using ionic-immobilized Rh-ligand complexes on the LDH. The Rh-TPPTS/Zn 3 AlCl was found to exhibit a pretty high activity and selectivity for such reactions leading to heteropolycyclic derivatives. The heterogeneous catalyst was easily recycled with no leaching. © 2007 Elsevier B.V. All rights reserved. Keywords: Cycloaddition; Microwaves; Hydrogenation; Heterogeneous catalysis; Rhodium; Bicyclo[2.2.2]octenes 1. Introduction Bicyclo[2.2.2]octenes and their fused derivatives [1] as well as their hydrogenated analogues, bicyclo[2.2.2]octanes, [1c,2] have been shown to serve as useful building blocks in organic syntheses. Among them, bicyclo[2.2.2]oct-7-enes (bicyclo[2.2.2]oct-2-enes when unsubstituted) containing a free ∗ Corresponding author. Tel.: +40 21 4100241; fax: +40 21 4100241. ∗∗ Corresponding author. Tel.: +34 923294489. ∗∗∗ Corresponding author. Tel.: +386 12419230; fax: +386 12419220. ∗∗∗∗ Corresponding author. Tel.: +33 144276742; fax: +33 144071062. E-mail addresses: v parvulescu@chem.unibuc.ro, v parvulescu@yahoo.com (V.I. Parvulescu), vrives@usal.es (V. Rives), marijan.kocevar@fkkt.uni-lj.si (M. Koˇ cevar), veronique-michelet@enscp.fr (V. Michelet). or protected amino group at the bridgehead carbon atom are very rare compounds [3a] and can be found in the skeleton of naturally occurring Kopsia alkaloids [3b] whereas analo- gous bicyclo[2.2.2]octanes have been only rarely described. During our recent investigation of the transformations of the 2H-pyran-2-ones and fused pyran-2-ones we synthesized a series of aminobicyclo[2.2.2]oct-7-enes bearing fused het- erocyclic rings in their structure, such as a fused maleic anhydride moiety [4a] or a fused substituted succinimide moiety [4b,c]. The transformation of the bicyclo[2.2.2]oct-7-ene- 2exo,3exo,5exo,6exo-tetracarboxylic acid 2,3:5,6-dianhydrides with hydrazine derivatives resulted in the preparation of the corresponding fused succinimides [5]. Over the past few years the developments in the field of green chemistry have been oriented towards adopting methods and processes that use less-toxic chemicals, produce smaller 1381-1169/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.molcata.2007.06.018