oa Editorial [Hot Topic: Green and Sustainable Chemistry (Guest Editor: Bela Torok)

The application of the principals of Green Chemistry are becoming more and more common in organic synthesis, and the design of sustainable synthetic methods is more important today than ever. The volume of the industrial production of chemicals, pharmaceuticals, agrochemicals, or consumer goods directly related to the chemical industry (e.g. plastics, dyes etc.), makes the traditional ways obsolete and impossible to continue due to the strengthening environmental and safety concerns. In this special issue, our goal was to provide an overview, as broad as possible, about recent developments in the design of sustainable methods. While we certainly understand that green organic synthesis is much broader than what one can cover in this issue, nevertheless, several areas are discussed from catalysis, through fluorous chemistry to peptide synthesis. Interestingly, several articles in this issue deal with palladium-catalyzed coupling reactions, such as Heck, Suzuki, or Negishi couplings, for which their developers Heck, Suzuki and Negishi just have been awarded the Nobel Prize in Chemistry in 2010. The first part of the issue summarizes recent developments in the applications of heterogeneous catalytic methods in sustainable synthesis. The first paper is a review by B. C. Ranu and his colleagues that focuses on the application of supported metal catalysts in a broad variety of reactions including palladium, copper, ruthenium or rhodiummediated reactions. The next article by A. Molnar summarizes the new developments in sustainable Heck chemistry with palladium catalysts. The emphasis is placed on palladium catalysts of recyclable character. Continuing with metal-catalyzed reactions A. Kulkarni and B. Torok provide an update on heterogeneous metal-catalyzed hydrogenations, focusing on the application of commercially available metal catalysts. With a shift in the catalysis part, Y. Chang and C. Bae give an overview on the use of polymer supported catalysts in synthesis. The work summarizes numerous examples of Brønsted and Lewis acids immobilized on polymer surfaces. A variety of reactions from Friedel-Crafts chemistry to multicomponent reactions are covered in this review. The last account in the catalysis section by B. Torok and his coworkers reviews recent developments on microwave-assisted heterogeneous catalysis, including both solid acid and supported metal-catalyzed reactions. The other papers cover different aspects of sustainable synthesis design. As an example, M. Torok and her co-workers summarize and discuss steps that were made toward green peptide synthesis. With the broad use of peptides in many fields, the need is certainly pressing given the nature of these reactions. In the next work J. Han and coworkers describe the use of another strong contributor to green synthesis; biomimetic reactions, in particular, biomimetic transaminations. The work highlights the importance of these metal-free reactions in the synthesis of fluorinated amines and amino acids. W. Zhang and his coworkers provide a detailed account on the application of microwaveassisted fluorous multicomponent reactions; an approach that significantly contributes to combinatorial chemistry. Last but not least, V. A. Soloshonok and his coworkers summarize the developments in an exciting new area of optical purification. While this area is still in its infancy compared to the commonly applied methods of chiral purification, sublimation may become a mainstream green separation method for chiral compounds. We can conclude that these reviews while do not cover every aspect of green organic synthesis, provide a diverse picture of several areas; traditional ones such as catalytic methods, or microwave-assisted synthesis, and really unique works on possibilities of green peptide synthesis or optical purification by sublimation. I feel that this broad coverage will make this issue attractive for synthetic chemists working in industry or academia. Finally, as a guest editor for this special issue, I am very grateful for the valuable and excellent contributions from my colleagues and I am also highly appreciative of the referees for their expert comments. My sincere thanks are also due to Ms. Humaira Hashmi (Sr. Manager Publications, Current Organic Synthesis) and Ms. Maria Baig (Assistant Manager Publications, Current Organic Synthesis) for their help in the organization of this issue.