-Selective C-H Functionalization of Arylsilanes Using a Silicon Tethered Directing Group.

We describe -selective C-H functionalization of arylsilanes using a Si-tethered directing group. The current method enables a selective alkenylation of arenes bearing a variety of functional groups, and several electron-deficient olefins are also applicable as coupling partners. Further functional group transformations of the silicon-tethered directing group provide multisubstituted arenes efficiently.

A Simple Benchtop Filtration Method to Isolate Small Extracellular Vesicles from Human Mesenchymal Stem Cells.

The ultracentrifugation-based process is considered the common method for small extracellular vesicles (sEVs) isolation. However, the yield from this isolation method is relatively lower, and these methods are inefficient in separating sEV subtypes. This study demonstrates a simple benchtop filtration method to isolate human umbilical cord-derived MSC small extracellular vesicles (hUC-MSC-sEVs), successfully separated by ultrafiltration from the conditioned medium of hUC-MSCs.

Use of Green Solvents in Metallaphotoredox Cross-Electrophile Coupling Reactions Utilizing a Lipophilic Modified Dual Ir/Ni Catalyst System.

Facilitating photoredox coupling reactions in process-friendly green solvents was achieved by the successful application of a dual Ir/Ni catalyst system with enhanced solubility properties. These photochemical reactions (specifically Br-Br sp-sp cross electrophile coupling) are reported in a head to head comparison to the standard di--Bu bipyridine ligand Ir/Ni catalyst system. This presentation highlights the benefits of altering the solubility properties of the ligands used in the Ir/Ni dual catalyst.

Induction of Apoptosis and Autophagy by Ternary Copper Complex Towards Breast Cancer Cells.

Background: Copper complex has been gaining much attention in anticancer research as a targeted agent since cancer cells uptake more copper than non-cancerous cells. Our group synthesised a ternary copper complex, which is composed of 1,10-phenanthroline and tyrosine [Cu(phen)(L-tyr)Cl].3H0.

High body mass index and sleep problems during pregnancy: A meta-analysis and meta-regression of observational studies.

Despite the well-established correlation of weight and sleeping problems, little is known about the nature of the association. The present study examined whether pregnant women with high body mass index have a risk of developing sleep problems, and identified any covariates that affect this relationship. We systematically searched electronic databases, specialized journals, various clinical trial registries, grey literature databases and the reference list of the identified studies.

Benchtop Isolation and Characterisation of Small Extracellular Vesicles from Human Mesenchymal Stem Cells.

The objective of this study is to develop a simple protocol to isolate and characterise small extracellular vesicles (sEVs) from human umbilical cord-derived MSCs (hUC-MSCs). hUC-MSCs were characterised through analysis of morphology, immunophenotyping and multidifferentiation ability. SEVs were successfully isolated by ultrafiltration from the conditioned medium of hUC-MSCs.

Understanding Flavin-Dependent Halogenase Reactivity via Substrate Activity Profiling.

The activity of four native FDHs and four engineered FDH variants on 93 low molecular weight arenes was used to generate FDH substrate activity profiles. These profiles provided insights into how substrate class, functional group substitution, electronic activation, and binding impact FDH activity and selectivity. The enzymes studied could halogenate a far greater range of substrates than previously recognized, but significant differences in their substrate specificity and selectivity were observed.

Inverting Conventional Chemoselectivity in Pd-Catalyzed Amine Arylations with Multiply Halogenated Pyridines.

A new catalyst system capable of selective chloride functionalization in the Pd-catalyzed amination of 3,2- and 5,2- Br/Cl-pyridines is reported. A reaction optimization strategy employing ligand parametrization led to the identification of 1,1'-bis[bis(dimethylamino)phosphino]ferrocene "DMAPF", a readily available yet previously unutilized diphosphine, as a uniquely effective ligand for this transformation.

Induced pluripotent stem cells from human hair follicle keratinocytes as a potential source for hair follicle cloning.

Background: Human hair follicles are important for the renewal of new hairs and their development. The generation of induced pluripotent stem cells (iPSCs) from hair follicles is easy due to its accessibility and availability. The pluripotent cells derived from hair follicles not only have a higher tendency to re-differentiate into hair follicles, but are also more suited for growth in hair scalp tissue microenvironment.

Sequential Regioselective C-H Functionalization of Thiophenes.

Herein, the sequential functionalization of 5-membered ring heterocycles is disclosed. By employing a pH sensitive directing group both directed and nondirected C-H activation pathways are available, providing access to 2,3,4- and 2,4,5-substituted thiophenes. The C-H arylation was performed in water, and using a surfactant greatly improved the yield and mass recovery.

Synthesis of 5'-O-DMT-2'-O-TBS Mononucleosides Using an Organic Catalyst.

This unit describes a highly effective method to produce 5'-O-DMT-2'-O-TBS mononucleosides selectively using a small organic catalyst. This methodology avoids the tedious protection/deprotection strategy necessary to differentiate the 2'- and 3'-hydroxyl groups in a ribonucleoside. The catalyst was synthesized in two steps, starting from the condensation of valinol and cyclopentyl aldehyde, followed by anionic addition of N-methylimidazole.

Distal-selective hydroformylation using scaffolding catalysis.

In hydroformylation, phosphorus-based directing groups have been consistently successful at placing the aldehyde on the carbon proximal to the directing group. The design and synthesis of a novel catalytic directing group are reported that promotes aldehyde formation on the carbon distal relative to the directing functionality. This scaffolding ligand, which operates through a reversible covalent bond to the substrate, has been applied to the diastereoselective hydroformylation of homoallylic alcohols to afford δ-lactones selectively.

Meta-selective C-H functionalization using a nitrile-based directing group and cleavable Si-tether.

A nitrile-based template that enables meta-selective C-H bond functionalization was developed. The template is applicable to a range of substituted arenes and tolerates a variety of functional groups. The directing group uses a silicon atom for attachment, allowing for a facile introduction/deprotection strategy increasing the synthetic practicality of this template.

Resolution of terminal 1,2-diols via silyl transfer.

Through kinetic analysis and optimization, we report an improved resolution of terminal 1,2-diols via asymmetric silyl transfer. Because the reaction is a regiodivergent resolution, the monoprotected product could be isolated in excess of 95:5 er and 40% yield. The described method offers a means of chemically differentiating a terminal 1,2-diol with concomitant resolution of the enantiomers.

Practical silyl protection of ribonucleosides.

Herein we report the site-selective silylation of the ribonucelosides. The method enables a simple and efficient procedure for accessing suitably protected monomers for automated RNA synthesis. Switching to the opposite enantiomer of the catalyst allows for the selective silylation of the 3'-hydroxyl, which could be used in the synthesis of unnatural RNA or for the analoging of ribonucelosides.

Catalyst recognition of cis-1,2-diols enables site-selective functionalization of complex molecules.

Carbohydrates and natural products serve essential roles in nature, and also provide core scaffolds for pharmaceutical agents and vaccines. However, the inherent complexity of these molecules imposes significant synthetic hurdles for their selective functionalization and derivatization. Nature has, in part, addressed these issues by employing enzymes that are able to orient and activate substrates within a chiral pocket, which increases dramatically both the rate and selectivity of organic transformations.

The efficient desymmetrization of glycerol using scaffolding catalysis.

Glycerol is an ideal building block for the synthesis of complex molecules, because it is inexpensive and highly functionalized. We report the desymmetrization of glycerol through silyl transfer, using a chiral organic catalyst in high yield and enantioselectivity.

Site-selective catalysis: toward a regiodivergent resolution of 1,2-diols.

This paper demonstrates that the secondary hydroxyl can be functionalized in preference to the primary hydroxyl of a 1,2-diol. The site selectivity is achieved by using an enantioselective organic catalyst that is able to bond to the diol reversibly and covalently. The reaction has been parlayed into a divergent kinetic resolution on a racemic mixture, providing access to highly enantioenriched secondary-protected 1,2-diols in a single synthetic step.

Scaffolding Catalysis: Expanding the Repertoire of Bifunctional Catalysts.

Inducing an intramolecular reaction is a powerful means of accelerating reactions. Though this mechanism of catalysis is common in enzymes, it is underutilized in synthetic catalysts. This article outlines our group's recent efforts to use reversible covalent bonding to induce an intramolecular reaction, allowing for rate acceleration as well as control of the selectivity in the desymmetrization of 1,2-diols.

Enantioselective hydroformylation of aniline derivatives.

We have developed a ligand that reversibly binds to aniline substrates, allowing for the control of regioselectivity and enantioselectivity in hydroformylation. In this paper we address how the electronics of the aniline ring affect both the binding of the substrate to the ligand and the enantioselectivity in this reaction.

Scaffolding catalysts: highly enantioselective desymmetrization reactions.

Ex-changing places: a highly enantioselective desymmetrization of 1,2-diols has been developed in which the catalyst utilizes reversible covalent bonding to the substrate to achieve both high selectivity and rate acceleration (see scheme, PMP=pentalmethylpiperidine, TBS=tert-butyldimethylsilyl). Induced intramolecularity is responsible for the enhanced rate, thus allowing the reaction to be performed at room temperature.