All known forms of life use RNA-mediated polypeptide synthesis to produce the proteins encoded in their genes. Because the principal parts of the translational machinery consist of RNA, it is likely that peptide synthesis was achieved early in the prebiotic evolution of an RNA-dominated molecular world. How RNA attracted amino acids and then induced peptide formation in the absence of enzymes has been unclear. Herein, we show that covalent capture of an amino acid as a phosphoramidate favors peptide formation. Peptide coupling is a robust process that occurs with different condensation agents. Kinetics show that covalent capture can accelerate chain growth over oligomerization of the free amino acid by at least one order of magnitude, so that there is no need for enzymatic catalysis for peptide synthesis to begin. Peptide chain growth was also observed on phosphate-terminated RNA strands. Peptide coupling promoted by ribonucleotides or ribonucleotide residues may have been an important transitional form of peptide synthesis that set in when amino acids were first captured by RNA.

All knownf orms of life use RNA-mediated polypeptide synthesis to produce the proteins encoded in their genes.B ecause the principal parts of the translational machinery consist of RNA, it is likely that peptide synthesis was achieved early in the prebiotic evolution of an RNA-dominated molecular world. How RNAa ttracted amino acids and then induced peptide formation in the absence of enzymes has been unclear.H erein, we show that covalent capture of an amino acid as ap hosphoramidate favors peptide formation. Peptide coupling is ar obust process that occurs with different condensation agents.K inetics showt hat covalent capture can accelerate chain growth over oligomerization of the free amino acid by at least one order of magnitude,sothat there is no need for enzymatic catalysis for peptide synthesis to begin. Peptide chain growth was also observed on phosphate-terminated RNAs trands.P eptide coupling promoted by ribonucleotides or ribonucleotide residues may have been an important transitional form of peptide synthesis that set in when amino acids were first captured by RNA.

Enynes are important motifs in bioactive compounds. They can be synthesized by alkyne–alkyne couplings for which a number of mechanisms have been suggested depending on catalyst type and dominant product isomers. Regarding bimetallic pathways, hydrometalations and anti-carbopalladations have been discussed to account for the formation of geminally substituted and (Z)-configured enynes, respectively. Here we report a bimetallic alkyne–alkyne coupling that yields (E)-configured enynes. An unusual type of acetylide Pd bridging was found in putative catalytic intermediates which is arguably responsible for the regio- and stereochemical reaction outcome. Mechanistic studies suggest that a double μ–κ:η2 acetylide bridging enables a bimetallic syn-carbometalation. Interestingly, depending on the reaction conditions, it is also possible to form the geminal regioisomer as major product with the same catalyst. This regiodivergent outcome is explained by bi- versus monometallic reaction pathways.

Enantiopure fluorine containing β-amino acids are of large biological and pharmaceutical interest. Strategies to prepare β-amino acid derivatives possessing a F-containing tetrasubstituted stereocenter at the α-C atom in a catalytic asymmetric sense are rare, in particular using an enantioselective electrophilic C–F bond formation. In the present study, a highly enantioselective palladacycle-catalyzed fluorination of isoxazolinones was developed. It is demonstrated that isoxazolinones are useful precursors toward enantiopure β-amino acid derivatives by diastereo- and chemoselective reduction. The formed γ-aminoalcohols served as valuable precursors toward β-amino acids, β-amino acid esters, and β-lactams, all featuring tetrasubstituted fluorinated stereocenters. In addition, by this work, enantioenriched fluorinated azetidines were accessible for the first time.

A diastereospecific enantiodivergent allylation of pyrazolones is reported which is catalyzed by a planar chiral pentaphenylferrocene based palladacycle. With the same catalyst batch both product enantiomers were selectively available. The method is applicable to structurally diverse substrates and gave products with enantiomeric excesses between 85 and 94%. In addition, we could show that pyrazolones are transformable into β-aminoamides.