Search

Chiral allylic alcohols are highly prized in synthetic chemistry due to their versatile reactivity stemming from both alkenyl and hydroxyl functionalities. While the Nozaki–Hiyama–Kishi (NHK) reaction is a widely used method for the synthesis of allylic alcohols, it suffers from drawbacks such as the use of toxic chromium salts, high amounts of metal reductants, and poor enantiocontrol. To address these limitations, we present a novel approach involving a metallaphotoredox‐catalyzed asymmetric NHK reaction for the production of chiral allylic alcohols. This method marries alkenyl (pseudo)halides with aldehydes, leveraging a synergistic blend of a chiral nickel catalyst and a photocatalyst. This innovative technique enables both oxidative addition and insertion just using nickel, diverging significantly from the conventional NHK reaction pathway mediated by nickel and chromium salts. The adoption of this methodology holds immense promise for crafting a spectrum of intricate compounds, particularly those of significance in pharmaceuticals. Detailed experimental investigations have shed light on the metallaphotoredox process, further enhancing our understanding and enabling further advancements. [ABSTRACT FROM AUTHOR]

Transition‐metal‐catalyzed enantioselective addition of aryl organometallic reagents to imines has emerged as one of the most powerful tools for the formation of optically active diarylmethylamines. Here, we report the first asymmetric reductive (hetero)arylations of imines using aryl and heteroaryl halides enabled by a chiral cobalt‐bisphosphine catalyst. This approach shows good functional group compatibility and complements the reported strategy without use of organometallic reagents. Mechanistic investigations supported that aryl‐cobalt, instead of an arylzinc reagent, was formed in situ in this reductive aryl‐addition event. [ABSTRACT FROM AUTHOR]

Transition metal‐catalyzed C−H activation is a step‐economical strategy for peptide functionalization. Herein, we report the method of late‐stage peptide ligation and macrocyclization through rhodium‐catalyzed alkylation of tryptophan residues at the C7 position. This method utilizes a N‐PtBu2 directing group and tolerates various peptide and alkene substrates. Utilizing internal olefins, this study represents the first example of site‐selective peptide C−H alkylation through deconjugative isomerization. Furthermore, our method provides access to peptide macrocycles with unique Trp(C7)‐alkyl crosslinks and potent cytotoxicity towards cancer cells. [ABSTRACT FROM AUTHOR]

Chiral organoboronates have played a critical role in organic chemistry and in the development of materials science and pharmaceuticals. Much effort has been devoted to exploring synthetic methodologies for the preparation of these compounds during the past few decades. Among the known methods, asymmetric catalysis has emerged as a practical and highly efficient strategy for their straightforward preparation, and recent years have witnessed remarkable advances in this respect. Approaches such as asymmetric borylative addition, asymmetric allylic borylation and stereospecific cross-coupling borylation, have been extensively explored and well established employing transition-metal catalysis with a chiral ligand. This review provides a comprehensive overview of transition metal-catalysed asymmetric borylation processes to construct carbon–boron, carbon–carbon, and other carbon–heteroatom bonds. It summarises a range of recent achievements in this area of research, with considerable attention devoted to the reaction modes and the mechanisms involved. [ABSTRACT FROM AUTHOR]

Alkyl groups are one of the most widely used groups in organic synthesis. Here, a a series of thianthrenium salts have been synthesized that act as reliable alkylation reagents and readily engage in copper‐catalyzed Sonogashira reactions to build C(sp3)−C(sp) bonds under mild photochemical conditions. Diverse alkyl thianthrenium salts, including methyl and disubstituted thianthrenium salts, are employed with great functional breadth, since sensitive Cl, Br, and I atoms, which are poorly tolerated in conventional approaches, are compatible. The generality of the developed alkyl reagents has also been demonstrated in copper‐catalyzed Kumada reactions. [ABSTRACT FROM AUTHOR]

The first aromatic C−H silylation between arylphosphines and hydrosilanes enabled by a ruthenium complex has been developed. The excellent ortho‐selectivity results from a four‐membered metallacyclic intermediate involving phosphorus chelation. The developed system can be extended to the benzylic C−H silylation of arylphosphines. Diverse silylated arylphosphines are produced, exhibiting broad functional group compatibility. Further functionalization of the products under mild conditions renders the formed compounds useful building blocks. [ABSTRACT FROM AUTHOR]

A new InCl3-catalyzed addition reaction of 1,3-dicarbonyl compounds to various alkenes proceeded in good yields and can be carried out in air, which provided an easy and practical procedure for carbon-carbon bond formation. [ABSTRACT FROM AUTHOR]

Review: [40 refs. [ABSTRACT FROM AUTHOR]

This reaction yields unprotected indoles from 2-acetyl-1-arylhydrazines and alkynes without the need for an external oxidant. [ABSTRACT FROM AUTHOR]

This is the first Rh-catalyzed method for the synthesis of isoquinoline and pyridine N-oxides with an arylic or vinylic C-H activation as cyclization-initiating step. [ABSTRACT FROM AUTHOR]

A novel synthesis of azepinone derivatives by using a Rh-catalyzed intramolecular annulation reaction of N-substituted benzamides and α,β-unsaturated aldehydes and ketones is developed. [ABSTRACT FROM AUTHOR]

Depending on the reaction conditions this method can be used to synthesize naphthalene derivatives (III) as well as benzo[h]isoquinoline derivatives (VI). [ABSTRACT FROM AUTHOR]

Review: 19 refs. [ABSTRACT FROM AUTHOR]

The title reaction complements the Heck reaction on carbonyl substrates and provides substrates like aurones, e.g. (III), flavone (XVI), flavanone (XVII), and 2′-hydroxychalcones, e.g. (XIV), from readily available starting materials. [ABSTRACT FROM AUTHOR]

A nickel/N-heterocyclic carbene catalytic system is established for decarbonylative borylation of amides with Bnep2 by C-N bond activation. [ABSTRACT FROM AUTHOR]

Key to the regioselectivity is the choice of the phosphinoyl directing group and a pyridine-type ligand in the presence of Pd(OAc)2 as catalyst. [ABSTRACT FROM AUTHOR]

This protocol provides a powerful tool for late stage functionalization of complex molecules. [ABSTRACT FROM AUTHOR]

The catalytic system is capable of activating aryl and benzyl ammonium bonds for C-N borylation to produce a variety of organoborates. [ABSTRACT FROM AUTHOR]