Editorial [Hot Topic: Heterogeneous Catalysts in Organic Synthesis (Guest Editor: Arpad Molnar)]

This volume of Current Organic Chemistry is dedicated to the topic of the use of heterogeneous catalysts in organic synthesis. Catalysis, in general, plays a crucial and dominant role in chemistry, which may be best illustrated by the fact that about 90% of all the chemical processes applied in industry are catalytic transformations. Since the early 1990s, with the advent of green chemistry, there has been a strong driving force to replace homogeneous (soluble) catalysts with heterogeneous (solid) catalysts in chemical processes. Organic synthesis is an important field also benefiting from the achievements of catalysis research. This has been reflected in the tremendous development in the application of heterogeneous catalysts in organic synthesis in recent years. This special issue brings together experts of a few selected, important fields to highlight major achievements. The first three chapters in this volume are about asymmetric hydrogenations. The first review is a contribution from Tsutomu Osawa and his Toyama University group. They present a comprehensive summary of the application of asymmetrically modified Ni catalyst in the enantio-differentiating hydrogenation of prochiral ketones. In the second chapter Mihaly Bartok (University of Szeged) writes about the enantioselective hydrogenation of activated ketones over cinchonamodified Pt catalysts. In the third chapter Antal Tungler and his group (Budapest University of Technology and Economics) review asymmetric hydrogenation of the C=C bond focusing on the use of chirally modified Pd catalysts. C- C coupling reactions is a burgeoning field represented here by a paper written by Klaus Kohler and co-workers (Technische Universitat Munchen) evaluating the use of heterogeneous Pd catalysts in the Heck reaction. Two contributions disclose the use of versatile solids, successfully applied in a wide range of organic transformations. The review by Keith Smith and Gamal A. El-Hiti (University of Wales Swansea) focuses on their results with respect to regioselective electrophilic aromatic substitution reactions over reusable zeolites. The sixth chapter by François Figueras from the Institut de Recherches sur la Catalyse, Villeurbanne, and Mannepalli L. Kantam and Boyapati M. Choudary from the Indian Institute of Chemical Technology, Hyderabad, is about the application of solid base catalysts in organic synthesis focusing primarily on the use layered double hydroxides (hydrotalcites). The heterogeneous Meerwein-Ponndorf-Verly reduction, which has attracted special attention resulting in the development of various active solids, is treated accordingly in a review by Gaik K. Chuah and his group from the National University of Singapore. The next two papers represent specific approaches. The eighth chapter, provided by Ágnes Zsigmond and Ferenc Notheisz (University of Szeged) summarizes their results on the use of immobilized homogeneous complexes in selective syntheses. Masahiko Arai and his group from Hokkaido University, Sapporo are the contributors of the ninth chapter. They review the developments and applications of supported liquid phase catalysts. The final chapter in this volume is a contribution from myself and Bulcsu Rac (University of Szeged). This review surveys methods to prepare mesoporous silica materials and their derivatization by catalytically active functional groups. The main emphasis is on the catalytic application of the functionalized solids in synthetic transformations. It has been a pleasure to be involved as a Guest Editor with this issue of Current Organic Chemistry and I look forward to future involvement with this series. I would like to thank all the authors contributing to this issue for their efforts in making this issue interesting and informative. I hope you enjoy reading it.