Editorial: Forty Years and Counting

Abstract

Looking at the cover picture, you might be forgiven for thinking that Christmas has come a little early at the Asian Journal of Organic Chemistry. However, as seasonal as the Pacific Yew tree, Taxus brevifolia, looks, it is far from prematurely festive. This tree, or more specifically the fungi that reside in its bark, are the natural source of the anticancer drug paclitaxel, also known as taxol, and have in their own way played a small part in the history of the reaction that we celebrate in this special issue: the Mukaiyama aldol reaction. In 1973, Professor Teruaki Mukaiyama and his co-workers published a short paper on the directed aldol reaction.1 In a similar manner to a slightly earlier study on boron-mediated aldol reactions,2 they demonstrated that with the help of the Lewis acid titanium(IV) chloride, it is possible to control the aldol reaction to selectively obtain the cross-addition product of silyl enol ethers with aldehydes or ketones (Scheme 1). Simple though this reaction sounds, key questions of selectivity were solved and the aldol reaction was transformed from something in which some of the desired product could usually be fished out from among the condensation products into a directed, controllable reaction. The directed aldol reaction. Forty years on and the Mukaiyama aldol reaction, as it became known, still exerts an influence in modern organic chemistry. As this great advance in synthetic organic chemistry was further developed and used by chemists, it became a key reaction in total synthesis as a controllable and convenient way of introducing oxygen-based functional groups in a 1,3-pattern into complex molecules.3 Probably the most well-known example of this was published by Professor Mukaiyama himself as part of his total synthesis of taxol (Figure 1 and front cover) in 1999.4 In this route to the natural product, the directed aldol reaction was used repeatedly to introduce the correct stereochemical configuration. The natural product paclitaxel, also known as taxol. The continuing development of directed aldol reactions is especially evident in this special issue, which is packed with the most up-to-date research and includes contributions from former students and co-workers of Professor Mukaiyama, as well as recipients of the Society of Synthetic Organic Chemistry Japan′s Mukaiyama Award. Yanai et al. show us that in the reactions of lactones with silicon enolates it is possible to switch between aldol or olefination products by carefully choosing the catalyst, whereas Zhang and List bring us understanding of the kinetics behind chiral disulfonimide-catalyzed Mukaiyama aldol reactions. Shimizu and co-workers’ iodoaldol reaction of alkynylketone derivatives provides a convenient path towards multifunctionalized alkenes, and the concept of directed aldol polymerization of acetaldehyde is also demonstrated by Nozaki and co-workers. These papers are just a few examples of how the Mukaiyama aldol reaction continues to evolve today and promises to do so for years to come. Speaking of the Mukaiyama award, which recognizes outstanding contributions to organic chemistry by persons under the age of 45, our congratulations go to the two 2014 awardees, Phil Baran from the Scripps Research Institute, La Jolla, and Masayuki Inoue from the University of Tokyo, whose paper “The Orientation of the Terminal tBu Group of Antillatoxin is Important for Potent Toxicity: Design, Synthesis and Biological Evaluation of Conformationally Restricted Analogues of Antillatoxin” was published in the Asian Journal of Organic Chemistry earlier this year. This paper provides a fascinating insight into how subtle changes in structure can completely alter the toxicity of a molecule, and you can read it in issue eight from August. Apart from the practical side of his work, Professor Mukaiyama continues to be a great ambassador for chemistry. He has made enormous contributions to the Chemical Society of Japan, which co-owns the Asian Journal of Organic Chemistry and its sister journal Chemistry – An Asian Journal as part of the Asian Chemical Editorial Society (ACES). He is also a member of the Asian Journal of Organic Chemistry′s Honorary Board, and we thank him very much for his services. We hope that you enjoy reading this special issue and perhaps also gain an insight into what chemistry has in store for Mukaiyama aldol reaction the next forty years! 0 0 Dr. Richard Threlfall Managing Editor