LongLarf

Nature, Published online: 09 August 2022; doi:10.1038/s41586-022-05175-1

Nature, Published online: 11 August 2022; doi:10.1038/s41586-022-05167-1

Synlett
DOI: 10.1055/s-0042-1751358

A boronic acid catalyzed one-pot reduction of quinolines with Hantzsch ester followed by N-arylation via external base-free Chan–Evans–Lam coupling has been demonstrated. This step-economical synthesis of N-aryl tetrahydroquinolines has been accomplished from readily available quinoline, Hantzsch ester, and arylboronic acid under mild reaction conditions. The dual role of boronic acid as a catalyst (in the reduction of quinolines) and a reagent (in the N-arylation) has been realized for the first time. The use of an inexpensive N-arylation protocol, aerobic reaction conditions, and functional group diversity are important practical features.
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

Nature Catalysis, Published online: 19 August 2022; doi:10.1038/s41929-022-00827-x

Nature, Published online: 09 August 2022; doi:10.1038/s41586-022-05175-1

Build it better: Glycolaldehyde, which is obtainable from glucose or biomass pyrolysis oil, can be employed as a C₁ building block for the N-formylation of secondary amines. The reaction is highly efficient and requires only air as oxidant. The proposed radical mechanism was investigated by NMR and EPR spectroscopy and ESI-MS.

Abstract

Biomass derived glycolaldehyde was employed as C1 building block for the N-formylation of secondary amines using air as oxidant. The reaction is atom economic, highly selective and proceeds under catalyst free conditions. This strategy can be used for the synthesis of cyclic and acyclic formylamines, including DMF. Mechanistic studies suggest a radical oxidation pathway.

Recently developed fast cysteine bioconjugation reactions are summarized in this Concept, with a focus on the mechanisms and design principles that underlie the high efficiency of the new cysteine-modifying reagents.

Abstract

Cysteine bioconjugation serves as a powerful tool in biological research and has been widely used for chemical modification of proteins, constructing antibody-drug conjugates, and enabling cell imaging studies. Cysteine conjugation reactions with fast kinetics and exquisite selectivity have been under heavy pursuit as they would allow clean protein modification with just stoichiometric amounts of reagents, which minimizes side reactions, simplifies purification and broadens functional group tolerance. In this concept, we summarize the recent advances in fast cysteine bioconjugation, and discuss the mechanism and chemical principles that underlie the high efficiencies of the newly developed cysteine reactive reagents.

Highly enantioselective α-trifluoromethylated aliphatic, aromatic, and heterocyclic boronic acids and boronates were synthesized from simple feedstocks.

Abstract

A broad range of aliphatic, aromatic, and heterocyclic boronic acids were successfully homologated using trifluorodiazoethane in the presence of BINOL derivatives to provide the corresponding chiral trifluoromethyl containing boronic acid derivatives in high yields and excellent enantioselectivity. The in situ conversion of the chiral transient boronic acids to the corresponding alcohols or β-CF3 carboxylates are also demonstrated.

Synthesis
DOI: 10.1055/s-0040-1719884

This review provides an overview of different C1 building blocks as substrates of enzymes, or part of their cofactors, and the resulting­ functionalized products. There is an emphasis on the broad range of possibilities of biocatalytic one-carbon extensions with C1 sources of different oxidation states. The identification of uncommon biosynthetic strategies, many of which might serve as templates for synthetic or biotechnological applications, towards one-carbon extensions is supported by recent genomic and metabolomic progress and hence we refer principally to literature spanning from 2014 to 2020.1 Introduction2 Methane, Methanol, and Methylamine3 Glycine4 Nitromethane5 SAM and SAM Ylide6 Other C1 Building Blocks7 Formaldehyde and Glyoxylate as Formaldehyde Equivalents8 Cyanide9 Formic Acid10 Formyl-CoA and Oxalyl-CoA11 Carbon Monoxide12 Carbon Dioxide13 Conclusions
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

You (don't) spin me right ‘round, baby, right ‘round. A new organocatalytic atroposelective method for the construction of C−N atropisomers is presented. The newly developed F-substituted aminocatalyst, with an increased outer-sphere steric control, enables the atroposelective formation of the desired product, which feature interesting biological motifs.

Abstract

The first atroposelective aminocatalytic methodology for the construction of C−N atropisomers is presented. The synthesis of this class of axially chiral molecules typically encompasses substrates in which the C−N bond is pre-formed. In contrast, this work presents the direct coupling of indole-2-carboxaldehydes to ortho-quinones, to form the stereogenic C−N axis in an atroposelective way. Application of typical secondary amine catalysts furnished the desired product, however, in low yields and as a complex mixture arising from poor regiocontrol among the C₃- and N₁-sites of the indole core. A new aminocatalyst was designed and synthesized with increased outer-sphere steric bulk to address these challenges thereby providing good levels of regio- and enantioselectivity. A novel library of functionalized and enantioenriched C−N atropisomers was obtained and their synthetic utility was demonstrated by various transformations.