Annual Reports Section "B" (Organic Chemistry) (v.106, #00)
Front cover (1-2).
Introduction by Phil Page; Ian Cunningham (15-18).
Part (i) Free-radical reactions by Gareth J. Rowlands (19-33).
The preceding year has seen radical chemistry flourish in three areas; C–H activation, ‘green’ chemistry and enantioselective radical organocatalysis. The advances in these fields, which include the use of less expensive, milder reagents, sustainable energy sources and simple photoredox catalysis, will allow radical chemistry to find a wider acceptance.
Part (ii) Oxidation and reduction methods by Simon E. Lewis (34-75).
This Report highlights advances in some of the most commonly used oxidation and reduction reactions, focusing on the literature from 2009. The review is subdivided in a similar fashion to the author's previous review in this area.1 In the field of oxidation, salen complexes, oxaziridinium salts and carbohydrate-derived dioxiranes continue to attract much attention in the context of alkene epoxidation. Elsewhere, a significant disclosure from Que is the first system able to catalyse the dearomatising dihydroxylation of an arene59 and Katsuki has reported the use of a dimeric Fe “salan” (reduced salen) complex to catalyse oxidative dimerisation of naphthols, affording BINOLs that are themselves ligands for asymmetric synthesis.132 In the field of reduction, the development of novel chiral phosphine ligands remains a prominent subject of research for alkene hydrogenation. There is sustained interest in oxazaborolidines as catalysts for ketone reduction and several methods for direct asymmetric reductive alkylation are reported. A general trend seen is increased activity in the area of green chemistry and there have been many reports on the use of nanoparticles as catalysts.
Heteroatom methods by Jonathan P. Knowles; Andrew Whiting (76-97).
The report describes some advances in organooxygen and organonitrogen chemistry from 2009.
Organometallics: transition metals in organic synthesis by Paul W. Davies (98-119).
In organometallic chemistry for organic synthesis the development of powerful new transformations, the study and application of reactivity principles, the elucidation of reactive intermediates, and the preparation of new active catalyst systems have all received great attention in 2010.
Organocatalysis by Benjamin R. Buckley; Stephen P. Neary (120-135).
Reactions carried out with substoichiometric quantities of organic molecules as catalysts have received much attention over the past decade. This review highlights progress in 2009 towards highly enantioselective organocatalytic systems and the natural product/biologically active compounds that can be prepared using these types of processes.
Heterocyclic chemistry by Karl Hemming (136-155).
2009 offered several significant advances in the field of heterocyclic chemistry, with particular highlights including several new approaches to pyrroles, indoles and pyrimidines. Major themes were hydroamination processes, the development of new multi-component reactions and advances in the development of catalytic asymmetric electrocyclisations.
Marine natural products by Robert A. Hill (156-173).
This review covers the literature on marine natural products published in 2009. Natural products from a variety of marine sources with unusual structural features or interesting biological activities are highlighted. The compounds are organised loosely under their biogenetic origins of polyketides, terpenoids, alkaloids and peptides.
Synthesis highlights by Nadale K. Downer-Riley; Yvette A. Jackson (174-196).
This review covers a sample of the total syntheses of natural products reported in the chemical literature in 2009. Syntheses are grouped according to key reactions.
Supramolecular chemistry by Scott J. Dalgarno (197-215).
The year 2009 has seen many advances in supramolecular chemistry. This short review highlights a number that have been made by various research groups. In line with previous articles from this series, the review is split into three broad sections encompassing molecular recognition, structure and assembly, and functional systems.
Biotransformations by Gideon Grogan (216-242).
This report reviews significant developments in the application of biological catalysis in synthetic organic chemistry for the year 2009. The continuing interest in lipases as catalysts for quantitative asymmetric transformation has resulted in their application to the synthesis of norsertraline and imidacloprid using dynamic kinetic resolution approaches. A lipase has also been used for the resolution of a complex dynamic compound library based on the reversible Strecker reaction. Esterases have been engineered for wider substrate specificity, and, in one case, to acquire epoxide hydrolase activity. A fluorophosphatase has been engineered to display activity toward the more toxic enantiomer of the nerve agent sarin. A new process has been formulated for the laccase-dependent regeneration of NAD(P)H for use in reductase-catalysed processes. Laccases themselves are attracting increasing interest as mild oxidation catalysts for aromatic coupling reactions leading to polycyclic biologically active compounds and dyes. An amino acid residue in enoate reductases has been highlighted as a major factor in determining enantioselectivity in those enzymes. In carbon–carbon bond formation, aldolases that are able to accept the non-phosphorylated C3 donor dihydroxyacetone have been applied to the synthesis of iminosugars, and the first application of the enzymatic Friedel-Crafts reaction has been realised. Last, aminomutases have found application in the synthesis of β-amino acids, in one case being combined with alanine racemase, furnishing an elegant process for the quantitative conversion of α-phenylalanine to its β-isomer.
(N-Heterocyclic Carbene)-Metal Complexes and Their Application in Catalysis by Oscar Navarro; Mihai S. Viciu (243-259).
This review covers recent advances (2009) in synthesis and catalytic activity of carbene metal complexes. Due to the wide variety of research interests in this field and the limited space of this account, a selection of the papers needed to be made focusing on a comprehensive coverage of recent trends and potential impact on catalysis.
Part (i) Radical and radical ion reactions by J. M. Tanko (260-282).
This chapter examines, from a mechanistic perspective, the major advances in the area of radical and radical ion chemistry reported in 2009. Fundamental classes of radical/radical ion processes are presented (substitution and atom transfer, addition, and fragmentation). The creative design and implementation of multistep (cascading) radical processes in organic synthesis provides new tools for the preparation compounds of incredible structural diversity, and this chapter concludes with some recent examples.
Part (ii) Pericyclic reactions by Jeehiun K. Lee; Dean J. Tantillo (283-303).
This report surveys the 2009 literature on mechanisms of pericyclic reactions. Again, mechanistic studies of cycloadditions dominate, especially those of relevance to organic synthesis. Several electrocyclizations used in the synthesis of complex polycycles were also examined in detail, as were a number of sigmatropic shifts involving aza-polyenes.
Part (iii) Polar reactions by Anna K. Croft (304-324).
This review presents highlights from papers published in 2009 reporting the mechanistic studies of polar reactions, predominantly in solution. Articles discussed will be focused on those primarily describing experimental studies. Subheadings utilised in this review only indicate a rough guide to the specific topics covered—as is typical of modern mechanistic chemistry, many studies can fall under a number of possible categorisations.
Physical methods and techniques NMR spectroscopy by Mark Edgar (325-343).
NMR spectroscopy continues to evolve, with publications in 2009 providing an eclectic collection of applications, advances and incremental improvements. This article covers rapid acquisition methods, DNP, SQUID, new liquid-state methods, “easy” and “difficult” solid-state methods, and computational aspects of NMR spectroscopy. A significant landmark was achieved in 2009, with the commercial release of the 1000 MHz (1 GHz, 23.4 T) NMR magnet. Also, despite the headline grabbing 1 GHz magnet, there remains significant interest in Earth-field (54 μT) NMR. I am indebted to the great and the good whose work has been reported here, all credit is theirs; errors, omissions and blame are all mine.
Reactivity in organised assemblies by Lavinia Onel; Niklaas J. Buurma (344-375).
This report reviews the 2009 literature on reactivity in organised assemblies, with virtually all examples taken from literature covering aqueous systems. The report is broadly organised along the lines that we set out last year,1 but with the addition of a “miscellaneous” section containing two papers that we did not want to leave out of this report. Nevertheless, as always, we cannot and will not claim that this report provides an exhaustive review. Several main themes covered by this report were reviewed in 2009; Prins and Scrimin reviewed covalent capture which they defined as relying on “the combined use of covalent and noncovalent synthesis by taking advantage of their complementarity”,2 Peyralans and Otto reviewed recent highlights in systems chemistry,3 metallomicellar catalysis was reviewed by Tecilla et al.4 and one of us reviewed kinetic medium effects on organic reactions in aqueous colloidal solutions.5
Fluorescent sensors for ions based on organic structures by Emma B. Veale; Thorfinnur Gunnlaugsson (376-406).
This report highlights some of the developments in 2009 of fluorescent, and in some cases, dual fluorescent and colorimetric, sensors, that are based on organic structures, and that were developed for the sensing/recognition of anions and cations.
Computational organic chemistry by Steven M. Bachrach (407-427).
The 2009 literature pertaining to computational organic chemistry is summarized and reviewed. Highlights include a number of reactions where dynamic effects are critical towards understanding their mechanism, novel aromatic species, and the use of computations to aid in interpreting NMR spectra and the role of the catalyst in asymmetric organocatalysis.
Enantioselective catalysis by Ai-Lan Lee (428-446).
The following review highlights significant advances in the field of enantioselective catalysis in 2009. Key advances in enantioselective gold-catalysed reactions and alkene metathesis will be emphasised.
Bioinspired organic chemistry by Lilia Milanesi; Salvador Tomas (447-469).
This annual report reviews a selection of contributions from researchers in the field of organic chemistry broadly interpreted, which take inspiration from biomolecular systems. The report is divided in four sections: the first three sections discuss progresses in organic chemistry inspired by the major classes of biomolecules: nucleic acids, proteins and lipids. The fourth section, subtitled Systems Chemistry, was introduced for the first time last year and is devoted to organic chemistry inspired by the complexity of biomolecular systems. Although it was originally applied to self-replicating chemical systems and dynamic combinatorial libraries, the term Systems chemistry is now being applied to the study of the emerging properties within complex systems. The reader will notice that the manipulation of emerging properties of increasingly complex systems is implicit in much of the chemistry described in this report.
Back cover (470-470).