Rh(I)-Catalyzed Regio- and Enantioselective Ring Opening of Vinyl Cyclopropanes.

We describe a Rh(I) catalyzed asymmetric ring opening of vinyl cyclopropanes using aryl boronic acids as C-nucleophiles. When ferrocene-based chiral bisphosphines are used as ligands, the products are obtained with regioselectivities typically 99:1 r.r.

Virtual Homonuclear Decoupling in Direct Detection Nuclear Magnetic Resonance Experiments Using Deep Neural Networks.

Nuclear magnetic resonance (NMR) experiments are frequently complicated by the presence of homonuclear scalar couplings. For the growing body of biomolecular C-detected NMR methods, one-bond C-C couplings significantly reduce sensitivity and resolution. The solution to this problem has typically been to perform virtual decoupling by recording multiple spectra and taking linear combinations.

Intra-residue methyl-methyl correlations for valine and leucine residues in large proteins from a 3D-HMBC-HMQC experiment.

Methyl-TROSY based NMR experiments have over the last two decades become one of the most important means to characterise dynamics and functional mechanisms of large proteins and macromolecular machines in solution. The chemical shift assignment of methyl groups in large proteins is, however, still not trivial and it is typically performed using backbone-dependent experiments in a 'divide and conquer' approach, mutations, structure-based assignments or a combination of these. Structure-based assignment of methyl groups is an emerging strategy, which reduces the time and cost required as well as providing a method that is independent of a backbone assignment.

Arginine Side-Chain Hydrogen Exchange: Quantifying Arginine Side-Chain Interactions in Solution.

The rate with which labile backbone hydrogen atoms in proteins exchange with the solvent has long been used to probe protein interactions in aqueous solutions. Arginine, an essential amino acid found in many interaction interfaces, is capable of an impressive range of interactions via its guanidinium group. The hydrogen exchange rate of the guanidinium hydrogens therefore becomes an important measure to quantify side-chain interactions.

An Environmentally Responsive Reciprocal Replicating Network.

A reciprocal replication system is constructed from four building blocks, A, B, C, and D, which react in a pairwise manner through either a 1,3-dipolar cycloaddition or the condensation reaction between an amine and an aldehyde to create two templates, trans-T and T. These templates are equipped with complementary recognition sites-two carboxylic acids ( trans-T) or two 4,6-dimethylamidopyridines (T)-that enable each template to direct the formation of its complementary partner through two mutually reinforcing cross-catalytic pathways, in which the templates trans-T or T preorganize the appropriate building blocks within two catalytically active ternary complexes: [C•D• trans-T] and [A•B•T]. The template-directed processes within these complexes generate a heteroduplex [ trans-T•T], which is shown to possess significant stability through kinetic simulations and fitting.

A C-detected N double-quantum NMR experiment to probe arginine side-chain guanidinium N chemical shifts.

Arginine side-chains are often key for enzyme catalysis, protein-ligand and protein-protein interactions. The importance of arginine stems from the ability of the terminal guanidinium group to form many key interactions, such as hydrogen bonds and salt bridges, as well as its perpetual positive charge. We present here an arginine C-detected NMR experiment in which a double-quantum coherence involving the two N nuclei is evolved during the indirect chemical shift evolution period.