Definition of the term asymmetric synthesis—History and revision

Helmchen, Günter

doi:10.1002/chir.23536

Cited by 8 publications

(6 citation statements)

References 19 publications

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“…Frequently, the inversion barrier was measured. The most rewarding, elegant, and challenging method for obtaining enantiomerically pure compounds – the catalytic asymmetric synthesis [58] – was successfully applied to boron‐based enantiomerism only very recently. This development meets in an advantageous way the phenomenon that has been known for a longer time: the intense luminescence of tetra‐coordinate organoboron compounds that makes them promising light emitting materials.…”

Section: Discussionmentioning

confidence: 99%

Boron‐Based Enantiomerism

Braun

2024

Eur J Org Chem

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Boron‐based enantiomerism is fragile due to the inherent tendency of a dissociation of a ligand from tetra‐coordinate chiral boron complexes under formation of the achiral tri‐coordinate species. This review will present the different approaches in overcoming the inherent tendency of racemization in boron‐stereogenic compounds. When embedded in an environment of chiral ligands or substituents, configurationally stable boron stereogenic centers can form in a diastereoselective manner. Compounds incorporating boron as the exclusive stereogenic center are obtained by resolution of the racemic mixtures. The recently developed – much more efficient – methods of a catalytic, enantioselective creation of boron stereogenic compounds are highlighted in this review. Finally the chiroptical properties of enantiomerically pure boron complexes that makes them promising materials or devices are addressed.

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Section: Discussionmentioning

confidence: 99%

Boron‐Based Enantiomerism

Braun

2024

Eur J Org Chem

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“…This can take on several forms: favoring one isomer over another (i. e., stereoselectivity) or one reactive chemical group over another (i. e., chemoselectivity) and, if multiple copies of this chemical group are present on the molecule, favoring one site -one positionover all the others (i. e., regioselectivity). [1][2][3][4][5][6] Since a lack in selectivity may result in complex mixtures of unwanted products, the art of chemical synthesis relies on the development of reaction conditions that will maximize the sole formation of the desired compound. While this can be a challenging task, small molecules possess a limited number of reactive sites.…”

Section: Introductionmentioning

confidence: 99%

Site‐Selective Protein Conjugation by a Multicomponent Ugi Reaction

Koutsopetras,

Vaur,

Benazza

et al. 2024

Chemistry A European J

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The chemical bioconjugation of proteins has seen tremendous applications in the past decades, with the booming of antibody‐drug conjugates and their use in oncology. While genetic engineering has permitted to produce bespoke proteins featuring key (un‐)natural amino acid residues poised for site‐selective modifications, the conjugation of native proteins is riddled with selectivity issues. Chemoselective strategies are plentiful and enable the precise modification of virtually any residue with a reactive side‐chain; site‐selective methods are less common and usually most effective on small and medium‐sized proteins. In this context, we studied the application of the Ugi multicomponent reaction for the site‐selective conjugation of amine and carboxylate groups on proteins, and antibodies in particular. Through an in‐depth mechanistic methodology work supported by peptide mapping studies, we managed to develop a set of conditions allowing the highly selective modification of antibodies bearing N‐terminal glutamate and aspartate residues. We demonstrated that this strategy did not alter their affinity toward their target antigen and produced an antibody‐drug conjugate with subnanomolar potency. Excitingly, we showed that the high site selectivity of our strategy was maintained on other protein formats, especially on anticalins, for which directed mutagenesis helped to highlight the key importance of a single lysine residue.

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“…The definition of the terms “asymmetric synthesis” and “asymmetric reaction” has been the subject of past and ongoing debate [1,2] . For the present review, a simple version was adopted, wherein an asymmetric reaction is considered as “a stereoselective reaction (or reaction sequence) to give preferentially a chiral non‐racemic product containing one or more new elements of chirality”, as noted by Helmchen and based on IUPAC recommendations [1] . This includes both enantioselective and diastereoselective processes, but not ones where achiral reactants produce mixtures of racemic diastereomers.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Synthesis with Organoselenium Compounds – The Past Twelve Years

Stadel,

Back

2024

Chemistry A European J

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The discovery and synthetic applications of novel organoselenium compounds and their reactions proceeded rapidly during the past fifty years and such processes are now carried out routinely in many laboratories. At the same time, the growing demand for new enantioselective processes provided new challenges. The convergence of selenium chemistry and asymmetric synthesis led to key developments in the 1970s, although the majority of early work was based on stoichiometric processes. More recently, greater emphasis has been placed on greener catalytic variations, along with the discovery of novel reactions and a deeper understanding of their mechanisms. The present review covers the literature in this field from 2010 to early 2023 and encompasses asymmetric reactions mediated by chiral selenium‐based reagents, auxiliaries and, especially, catalysts. Protocols based on achiral selenium compounds in conjunction with other species of chiral catalysts, as well as reactions that are controlled by chiral substrates, are also included.

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Definition of the term asymmetric synthesis—History and revision

Cited by 8 publications

References 19 publications

Boron‐Based Enantiomerism

Boron‐Based Enantiomerism

Site‐Selective Protein Conjugation by a Multicomponent Ugi Reaction

Asymmetric Synthesis with Organoselenium Compounds – The Past Twelve Years

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