Prebiotically Plausible Organocatalysts Enabling a Selective Photoredox α‐Alkylation of Aldehydes on the Early Earth

Closs, Anna C.; Fuks, Elina; Bechtel, Maximilian; Trapp, Oliver

doi:10.1002/chem.202001514

Cited by 20 publications

(40 citation statements)

References 53 publications

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“…The by far most pronounced catalyst was 3 db with a selectivity of over 50 % after 24 h. As 3 db also represents the most active chiral catalyst in our studied α-alkylation system, a connection between preferred formation and activity is shown. [27] Whereas a strong bias in the formation of single species was observed in aqueous ammonia solution, water led to a more uniform distribution over time, except for a negligible amount of acetone incorporated in ring position 2. Directly at the beginning of the reaction, the ITO mixture resembled the expected kinetic distribution.…”

Section: Methodsmentioning

confidence: 99%

Dynamic Exchange of Substituents in a Prebiotic Organocatalyst: Initial Steps towards an Evolutionary System

2021

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All evolutionary biological processes lead to a change in heritable traits over successive generations. The responsible genetic information encoded in DNA is altered, selected, and inherited by mutation of the base sequence. While this is well known at the biological level, an evolutionary change at the molecular level of small organic molecules is unknown but represents an important prerequisite for the emergence of life. Here, we present a class of prebiotic imidazolidine-4-thione organocatalysts able to dynamically change their constitution and potentially capable to form an evolutionary system. These catalysts functionalize their building blocks and dynamically adapt to their (selfmodified) environment by mutation of their own structure. Depending on the surrounding conditions, they show pronounced and opposing selectivity in their formation. Remarkably, the preferentially formed species can be associated with different catalytic properties, which enable multiple pathways for the transition from abiotic matter to functional biomolecules.

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Section: Methodsmentioning

confidence: 99%

Dynamic Exchange of Substituents in a Prebiotic Organocatalyst: Initial Steps towards an Evolutionary System

2021

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“…Although it is clear that our model system using Gly only gives access to the simplest peptide structure i.e., Gly n , other chemical modifications such as prebiotic α‐alkylation protocols [68] could have given access to a larger diversity of peptides from Gly n , or provide the necessary building blocks to synthesize other amino acid precursors [68] . To determine if other amino acids could undergo mechanochemical peptide bond formation in the presence of TiO 2 , L‐alanine (Ala) was milled under the standard reaction conditions.…”

Section: Methodsmentioning

confidence: 99%

Mechanochemical Prebiotic Peptide Bond Formation**

et al. 2021

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The presence of amino acids on the prebiotic Earth, either stemming from endogenous chemical routes or delivered by meteorites, is consensually accepted. In contrast, prebiotically plausible pathways to achieve peptides from unactivated amino acids are still unclear since most oligomerization approaches rely on thermodynamically disfavored reactions in solution. Alternative hypotheses such as the prebiotic impact scenario postulate that the mechanical impacts from meteorites and geochemical phenomena played an important role in delivering exogenous material to Earth, thus providing the geochemical, mechanical, and thermal conditions to synthesize small prebiotic organic compounds in the absence of bulk liquid media. In this context, here we evaluate the applicability of mechanochemistry by ball milling for peptide bond formation under a prebiotic impact scenario. We found that the combination of mechanical forces and prebiotically plausible and ubiquitous minerals as activators enable the oligomerization of amino acids such as glycine in the absence of bulk water (or solvents) and at ambient temperature. Increasing the mechanochemical reactor's temperature is shown to favor the degree of polymerization concomitantly with the formation of cyclic glycine dimer [cyclo(Gly 2 ) or DKP], a product commonly considered as a dead-end in solution peptide bond formation. However, our study shows that DKP can be mechanochemically activated and used as a source for glycine oligomers. The findings of this research provide alternative mechanochemical routes towards oligopeptides and establish new synthetic approaches for prebiotic chemistry that are not limited by poor diffusion of the reactants, thus complementing the current alternating wetting and drying prebiotic environment strategy. File list (2) download file view on ChemRxiv Peptide paper.pdf (816.75 KiB) download file view on ChemRxiv Peptide paper-SI.pdf (1.79 MiB)

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“…Recently, we introduced imidazolidine‐4‐thione catalyzed α‐cyanomethylation of aldehydes at wavelengths of 365 nm and 405 nm free of classical photosensitizers. Furthermore, the same reaction conditions were successfully applied to the MacMillan photoredox organocatalyst …”

Section: Methodsmentioning

confidence: 99%

Investigation of Straightforward, Photoinduced Alkylations of Electron‐Rich Heterocompounds with Electron‐Deficient Alkyl Bromides in the Sole Presence of 2,6‐Lutidine

et al. 2020

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Alkylations of simple electron-rich heterocompounds deliver valuable target structures in bioorganic and medicinal chemistry. Herein, we present a straightforward and photosensitizer free approach for the photoinduced CC coupling of electron-rich unsaturated heterocompounds with alkyl bromides using 405 nm and 365 nm irradiation. Comprehensive mechanistic studies indicate the involvement of 2,6-lutidine in the formation of a non-covalently bound intermediate to which the function of a photosensitizer is attributed. UV/Vis spectra reveal the formation of a bathochromic shifted band when the elec-[a

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Prebiotically Plausible Organocatalysts Enabling a Selective Photoredox α‐Alkylation of Aldehydes on the Early Earth

Cited by 20 publications

References 53 publications

Dynamic Exchange of Substituents in a Prebiotic Organocatalyst: Initial Steps towards an Evolutionary System

Dynamic Exchange of Substituents in a Prebiotic Organocatalyst: Initial Steps towards an Evolutionary System

Mechanochemical Prebiotic Peptide Bond Formation**

Investigation of Straightforward, Photoinduced Alkylations of Electron‐Rich Heterocompounds with Electron‐Deficient Alkyl Bromides in the Sole Presence of 2,6‐Lutidine

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