Electrochemistry represents one of the most intimate ways of interacting with molecules. This review discusses advances in synthetic organic electrochemistry since 2000. Enabling methods and ...synthetic applications are analyzed alongside innate advantages as well as future challenges of electroorganic chemistry.
CH oxidation has a long history and an ongoing presence in research at the forefront of chemistry and interrelated fields. As such, numerous highly useful articles and reviews have been written on ...this subject. Logically, these are generally written from the perspective of the scope and limitations of the reagents employed. This Minireview instead attempts to emphasize chemoselectivity imposed by the nature of the substrate. Consequently, many landmark discoveries in the field of CH oxidation are not discussed, but hopefully the perspective taken herein will allow CH oxidation reactions to be more readily incorporated into synthetic planning.
Let the molecule do the talking: If CH bonds could talk, they would tell stories of inductive effects, conjugation, hyperconjugation, steric hindrance, and strain release. These stories are told from the perspective of synthetic planning and draw from the immense body of literature on the topic.
Unmet potential: Electrochemistry is the most simple and basic way of altering the redox‐states of organic molecules. Despite extensive studies and its demonstrated promise, it has yet to take off in ...mainstream synthesis. The reason is due to engineering challenges in instrument design.
An operationally simple method to employ nonactivated carboxylic acids as alkylating agents in the N-alkylation of heterocycles is reported through an electrochemically driven anodic decarboxylative ...process. A wide substrate scope across a range of heterocycles is demonstrated along with a series of applications that significantly reduce the step count required to access such medicinally relevant structures.
Aiming for the ideal synthesis Gaich, Tanja; Baran, Phil S
Journal of organic chemistry,
07/2010, Letnik:
75, Številka:
14
Journal Article
Recenzirano
The field of total synthesis has a rich history and a vibrant future. Landmark advances and revolutionary strides in the logic of synthesis have put the practicing chemist in the enviable position of ...being able to create nearly any molecule with enough time and effort. The stage is now set for organic chemists to aim for "ideality" in the way molecules are synthesized. This perspective presents a simple and informative definition of "ideality" and demonstrates its use during the self-evaluation of several syntheses from our laboratory.
This Perspective illustrates the defining characteristics of free radical chemistry, beginning with its rich and storied history. Studies from our laboratory are discussed along with recent ...developments emanating from others in this burgeoning area. The practicality and chemoselectivity of radical reactions enable rapid access to molecules of relevance to drug discovery, agrochemistry, material science, and other disciplines. Thus, these reactive intermediates possess inherent translational potential, as they can be widely used to expedite scientific endeavors for the betterment of humankind.
Redox Economy in Organic Synthesis Burns, Noah Z; Baran, Phil S; Hoffmann, Reinhard W
Angewandte Chemie (International ed.),
April 6, 2009, Letnik:
48, Številka:
16
Journal Article
Recenzirano
Stimulus package for organic synthesis: The economy of step and atom usage has been widely reviewed and acknowledged as being useful frameworks to evaluate the efficiency of synthesis. This Review ...brings to attention another form of economy which should be considered in the planning and evaluation of a multistep synthesis: redox economy. Several guidelines and examples are included to illustrate the logic of this approach and to stimulate the design of syntheses."Economy" is referred to as the thrifty and efficient use of material resources, as the principle of "minimum effort to reach a goal." More illuminating is: "the aim to portion one's forces in order to use as little as possible of them to reach a goal." Such statements certainly apply when the goal is to synthesize a complex target molecule. Redox economy then implies the use of as few redox steps as possible in the synthetic conquest of a target compound. While any sort of economy will help to streamline the effort of total synthesis, redox economy addresses a particularly weak area in present-day total synthesis. It is not enough to point out the present deficiencies, rather the purpose of this Review is to serve as a teaching tool for all practitioners of the field by giving and illustrating guidelines to increase redox economy in multistep organic synthesis.
A redox-economic method for the direct coupling of olefins that uses an inexpensive iron catalyst and a silane reducing agent is reported. Thus, unactivated olefins can be joined directly to ...electron-deficient olefins in both intra- and intermolecular settings to generate hindered bicyclic systems, vicinal quaternary centers, and even cyclopropanes in good yield. The reaction is not sensitive to oxygen or moisture and has been performed on gram-scale. Most importantly, it allows access to many compounds that would be difficult or perhaps impossible to access using other methods.
From menthol to cholesterol to Taxol, terpenes are a ubiquitous group of molecules (over 55,000 members isolated so far) that have long provided humans with flavours, fragrances, hormones, medicines ...and even commercial products such as rubber. Although they possess a seemingly endless variety of architectural complexities, the biosynthesis of terpenes often occurs in a unified fashion as a 'two-phase' process. In the first phase (the cyclase phase), simple linear hydrocarbon phosphate building blocks are stitched together by means of 'prenyl coupling', followed by enzymatically controlled molecular cyclizations and rearrangements. In the second phase (the oxidase phase), oxidation of alkenes and carbon-hydrogen bonds results in a large array of structural diversity. Although organic chemists have made great progress in developing the logic needed for the cyclase phase of terpene synthesis, particularly in the area of polyene cyclizations, much remains to be learned if the oxidase phase is to be mimicked in the laboratory. Here we show how the logic of terpene biosynthesis has inspired the highly efficient and stereocontrolled syntheses of five oxidized members of the eudesmane family of terpenes in a modicum of steps by a series of simple carbocycle-forming reactions followed by multiple site-selective inter- and intramolecular carbon-hydrogen oxidations. This work establishes an intellectual framework in which to conceive the laboratory synthesis of other complex terpenes using a 'two-phase' approach.
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