The impact of earth-abundant metals as a replacement for Pd in cross coupling reactions.

Substitution of one metal catalyst for another is not as straightforward as simply justifying this change based on the availability and/or cost of the metals. Methodologies to properly assess options for reaction design, including multiple factors like a metal's availability, cost, or environmental indicators have not advanced at the pace needed, leaving decisions to be made along these lines more challenging. Isolated indicators can lead to conclusions being made in too hasty a fashion.

A widely distributed metalloenzyme class enables gut microbial metabolism of host- and diet-derived catechols.

Catechol dehydroxylation is a central chemical transformation in the gut microbial metabolism of plant- and host-derived small molecules. However, the molecular basis for this transformation and its distribution among gut microorganisms are poorly understood. Here, we characterize a molybdenum-dependent enzyme from the human gut bacterium that dehydroxylates catecholamine neurotransmitters.

Biomechanical comparison of knotted and knotless stabilization techniques of the tarsal medial collateral ligament in cats: A cadaveric study.

Objective: To compare mechanical properties of intact feline medial collateral ligaments and three techniques for treatment of feline medial tarsal instability.

Study Design: Controlled laboratory study.

Sample Population: Forty-eight normal, adult feline tarsi.

Biocatalytic Friedel-Crafts Alkylation Using a Promiscuous Biosynthetic Enzyme.

The Friedel-Crafts alkylation is commonly used in organic synthesis to form aryl-alkyl C-C linkages. However, this reaction lacks the stereospecificity and regiocontrol of enzymatic catalysis. Here, we describe a stereospecific, biocatalytic Friedel-Crafts alkylation of the 2-position of resorcinol rings using the cylindrocyclophane biosynthetic enzyme CylK.

SnAP-eX Reagents for the Synthesis of Exocyclic 3-Amino- and 3-Alkoxypyrrolidines and Piperidines from Aldehydes.

SnAP-eX (tin amine protocol, exocyclic heteroatoms) reagents allow the single-step transformation of aldehydes and ketones into 2,3-disubstituted pyrrolidines and piperidines containing exocyclic amine or alkoxy groups. These saturated N-heterocycles are of importance in modern drug discovery approaches and are prepared in moderate yields using an operationally simple protocol that is compatible with a range of functional groups and heterocyclic aldehydes.

Catalytic Synthesis of N-Unprotected Piperazines, Morpholines, and Thiomorpholines from Aldehydes and SnAP Reagents.

Commercially available SnAP (stannyl amine protocol) reagents allow the transformation of aldehydes and ketones into a variety of N-unprotected heterocycles. By identifying new ligands and reaction conditions, a robust catalytic variant that expands the substrate scope to previously inaccessible heteroaromatic substrates and new substitution patterns was realized. It also establishes the basis for a catalytic enantioselective process through the use of chiral ligands.

Synthesis of maculalactone A and derivatives for environmental fate tracking studies.

Maculalactone A (1) constitutes a promising antifouling agent, inhibiting the formation of biofilms in marine and freshwater systems. In this study, we developed a new route, based on a late-stage formation of the butenolide core, leading to the total synthesis of maculalactone A (three steps, overall yield of 45%) and delivering material on a gram scale. In addition, analogues of the title compound were assayed concerning their biological activity, utilizing Artemia franciscana and Thamnocephalus platyurus.

SnAP reagents for the one-step synthesis of medium-ring saturated N-heterocycles from aldehydes.

Interest in saturated N-heterocycles as scaffolds for the synthesis of bioactive molecules is increasing. Reliable and predictable synthetic methods for the preparation of these compounds, especially medium-sized rings, are limited. We describe the development of SnAP (Sn amino protocol) reagents for the transformation of aldehydes into seven-, eight- and nine-membered saturated N-heterocycles.

SnAP reagents for the synthesis of piperazines and morpholines.

Substituted piperazines and morpholines are valuable structural motifs in biologically active compounds, but are not easily prepared by contemporary cross-coupling approaches. In this report, we introduce SnAP reagents for the transformation of aldehydes into N-unprotected piperazines and morpholines. This approach offers simple, mild conditions compatible with aromatic, heteroaromatic, aliphatic, and glyoxylic aldehydes and provides mono- and disubstituted N-heterocycles in a single step.