In the last 30 years, C⁻C cross coupling reactions have become a reliable technique in organic synthesis due their versatility and efficiency. While drawbacks have been experienced on an industrial ...scale with the use of homogenous systems, many attempts have been made to facilitate a heterogeneous renaissance. Thus, this review gives an overview of the current status of the use of heterogeneous catalysts particularly in Suzuki and Heck reactions. Most recent developments focus on palladium immobilised or supported on various classes of supports, thus this review highlights and discuss contributions of the last decade.
The beginning of the 21st century has seen tremendous growth in the field of decarboxylative activation. Benzoic acid derivatives are now recognised as atom‐economic alternatives to traditional ...cross‐coupling partners, and they also benefit from being inexpensive, readily available and shelf‐stable reagents. In this microreview we discuss recent developments in the coupling of benzoic acid derivatives either with an arene or with a second benzoic acid derivative, a process often termed decarboxylative oxidative cross‐coupling. These procedures offer great promise for the development of highly selective and atom‐economic cross‐couplings.
Developing efficient and selective routes for biaryl synthesis is of great interest. Decarboxylative oxidative coupling is appealing, because both substrate classes are readily available, and only CO2 and H2O are formed as side products. Furthermore, the carboxyl group offers a site for selective transformations. This review details decarboxylative oxidative coupling from 2008 to the present.
Acyl Suzuki cross-coupling involves the coupling of an organoboron reagent with an acyl electrophile (acyl halide, anhydride, ester, amide). This review provides a timely overview of the very ...important advances that have recently taken place in the acylative Suzuki cross-coupling. Particular emphasis is directed toward the type of acyl electrophiles, catalyst systems and new cross-coupling partners. This review will be of value to synthetic chemists involved in this rapidly developing field of Suzuki cross-coupling as well as those interested in using acylative Suzuki cross-coupling for the synthesis of ketones as a catalytic alternative to stoichiometric nucleophilic additions or Friedel-Crafts reactions.
Radical–radical couplings are mostly nearly diffusion‐controlled processes. Therefore, the selective cross‐coupling of two different radicals is challenging and not a synthetically valuable ...transformation. However, if the radicals have different lifetimes and if they are generated at equal rates, cross‐coupling will become the dominant process. This high cross‐selectivity is based on a kinetic phenomenon called the persistent radical effect (PRE). In this Review, an explanation of the PRE supported by simulations of simple model systems is provided. Radical stabilities are discussed within the context of their lifetimes, and various examples of PRE‐mediated radical–radical couplings in synthesis are summarized. It is shown that the PRE is not restricted to the coupling of a persistent with a transient radical. If one coupling partner is longer‐lived than the other transient radical, the PRE operates and high cross‐selectivity is achieved. This important point expands the scope of PRE‐mediated radical chemistry. The Review is divided into two parts, namely 1) the coupling of persistent or longer‐lived organic radicals and 2) “radical–metal crossover reactions”; here, metal‐centered radical species and more generally longer‐lived transition‐metal complexes that are able to react with radicals are discussed—a field that has flourished recently.
The “persistent radical effect” (PRE) is a kinetic phenomenon explaining the high cross‐selectivity of radical–radical couplings. If two radicals with different lifetimes are generated at equal rates, the longer‐lived (persistent) radical will be accumulated in comparison to the short‐lived radical, resulting in a high cross‐coupling selectivity. Importantly, radical metal species also act as persistent coupling partners.
A large number of diversely functionalized analogs of the bioactive natural products neocryptolepine and isocryptolepine have been prepared from a series of 3‐bromoquinoline derivatives. The ...neocryptolepines were obtained by a Pd0‐catalyzed C−C bond coupling followed by C−N bond formation in yields up to 80 %, whereas the indoloquinolines were prepared by a Suzuki‐Miyaura cross‐coupling followed by azidation‐photochemical cyclization in yields ranging from traces to 95 % yield.
The synthesis of complex alkyl boronic esters through conjunctive cross‐coupling of vinyl boronic esters with carboxylic acids and aryl iodides is described. The reaction proceeds under mild ...metallaphotoredox conditions and involves an unprecedented decarboxylative radical addition/cross‐coupling cascade of vinyl boronic esters. Excellent functional‐group tolerance is displayed, and application of a range of carboxylic acids, including secondary α‐amino acids, and aryl iodides provides efficient access to highly functionalized alkyl boronic esters. The decarboxylative conjunctive cross‐coupling was also applied to the synthesis of sedum alkaloids.
One‐step to molecular complexity: A decarboxylative conjunctive cross‐coupling of carboxylic acids, vinyl boronic esters, and aryl iodides is described. The reaction proceeds under mild metallaphotoredox conditions and utilizes readily available feedstock materials, including secondary α‐amino acids, to access highly functionalized benzylic boronic esters in a single step.
The Buchwald–Hartwig Amination After 25 Years Dorel, Ruth; Grugel, Christian P.; Haydl, Alexander M.
Angewandte Chemie International Edition,
November 25, 2019, Letnik:
58, Številka:
48
Journal Article
Recenzirano
Odprti dostop
The Pd‐catalyzed coupling of aryl (pseudo)halides and amines is one of the most powerful approaches for the formation of C(sp2)−N bonds. The pioneering reports from Migita and subsequently Buchwald ...and Hartwig on the coupling of aminostannanes and aryl bromides rapidly evolved into general and practical tin‐free protocols with broad substrate scope, which led to the establishment of what is now known as the Buchwald–Hartwig amination. This Minireview summarizes the evolution of this cross‐coupling reaction over the course of the past 25 years and illustrates some of the most recent applications of this well‐established methodology.
The first quarter century: The Buchwald–Hartwig amination enables the formation of C(sp2)−N bonds through the Pd‐catalyzed coupling of (hetero)aryl halides and pseudohalides with amines. This Minireview discusses the development of this methodology over the past 25 years, including highlights of some of the most recent applications.
In the presence of trialkylaluminum reagents, diverse aryl methyl ethers can be transformed into valuable products by C−O bond‐cleaving alkylation, for the first time without the limiting β‐hydride ...elimination. This new nickel‐catalyzed dealkoxylative alkylation method enables powerful orthogonal synthetic strategies for the transformation of a variety of naturally occurring and easily accessible anisole derivatives. The directing and/or activating properties of aromatic methoxy groups are utilized first, before they are replaced by alkyl chains in a subsequent coupling process.
The activation of the C−OMe bond in the title reaction is facilitated by Lewis acidic trialkylaluminum compounds, which enhance the oxidative‐addition and transmetalation steps. A nickel catalyst with a bidentate P,P‐ligand prevents the competing β‐hydride elimination so that the alkyl‐substituted products are obtained in high yields.
Design and Synthesis of Spirocycles Kotha, Sambasivarao; Panguluri, Nageswara Rao; Ali, Rashid
European journal of organic chemistry,
October 2, 2017, Letnik:
2017, Številka:
36
Journal Article
Recenzirano
In this account we disclose a variety of simple strategies demonstrated in our laboratory in the last two decades for the assembly of diverse and intricate molecular frameworks containing spiro ...linkage(s) by using various metathesis protocols such as ring‐closing metathesis (RCM), ring‐opening cross‐metathesis (ROCM), ring‐closing enyne metathesis (RCEM) and ring‐rearrangement metathesis (RRM). Also, cycloaddition reactions (2+2, 4+2 and 2+2+2) and other key processes such as Claisen rearrangement (CR), Grignard addition, Fischer indolization (FI), Suzuki–Miyaura (SM) cross‐coupling and the retro‐Diels–Alder (rDA) reaction have been used as key steps to construct spirocycles.
In this personal account, a variety of spirocycles were constructed by sequential use of metathesis and cycloaddition reactions along with different name reactions such as Claisen rearrangement (CR), Grignard addition, Fischer indolization (FI), Suzuki–Miyaura (SM) cross‐coupling and the retro‐Diels–Alder (rDA) reaction as key steps.
Enol and phenol functionalities are very common in organic molecules. Utilization of these materials is very appealing in organic synthesis because they are important alternatives to organohalides in ...cross‐coupling reactions. In this review, we summarize the transition‐metal‐catalyzed cross‐coupling of enol‐ and phenol‐based electrophiles, including phosphates, sulfonates, ethers, carboxylates, and phenolates.
Coupled up! Protected enol and phenol compounds are important alternatives to organohalides in cross‐coupling reactions. The transition‐metal‐catalyzed cross‐coupling of enol‐ and phenol‐based electrophiles, including phosphates, sulfonates, ethers, carboxylates, and phenolates, have been summarized (see scheme; PG=protecting group).
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