Enantioselective Total Synthesis of (−)-Finerenone Using Asymmetric Transfer Hydrogenation

(−)-Finerenone is a nonsteroidal mineralocorticoid receptor antagonist currently in phase III clinical trials for the treatment of chronic kidney disease in type 2 diabetes. It contains an unusual dihydronaphthyridine core. We report a 6-step synthesis of (−)-finerenone, which features an enantioselective partial transfer hydrogenation of a naphthyridine using a chiral phosphoric acid catalyst with a Hantzsch ester. The process is complicated by the fact that the naphthyridine exists as a mixture of two atropisomers that react at different rates and with different selectivities. The intrinsic kinetic resolution was converted into a kinetic dynamic resolution at elevated temperature, which enabled us to obtain (−)-finerenone in both high yield and high enantioselectivity. DFT calculations have revealed the origin of selectivity.     

A general and convenient route to oxazolyl ligands

A diverse range of chiral and achiral oxazolyl ligands, which have many applications including catalysis and luminescent devices, are synthesized simply in three steps from readily available and inexpensive phenol and amino alcohol starting materials. The method can be applied to ligands with electron-donating/-withdrawing and sterically demanding/undemanding substituents, and can conveniently be scaled up to >25 g of product.     

Synthesis and Characterization of Tris(diethyldithiocarbamato) cobalt(III) as an Undergraduate Inorganic Laboratory

The synthesis of tris(diethyldithiocarbamato) cobalt(III) by the reaction of sodium diethyldithio-carbamate and cobaltous chloride is described. The recovered crystals of the cobalt complex are characterized by magnetic susceptibility, IR and NMR spectroscopy, and cyclic voltammetry.     

Stiffness and hysteretic energy loss of a reinforced-concrete shear wall

A static, cyclic test of one of the largest reinforced concrete shear walls to be investigated in a laboratory is reported. The test was performed to study the dynamic characteristics (stiffness and hysteretic energy loss) of the shear wall. Very sensitive displacement gages are needed to measure the small deformations. The large forces required to load the structure make the test results susceptible to deformation of the support fixture. With these concerns in mind, instrumentation and data-reduction methods were developed that could separate model deformations from displacements caused by support motion. Also, model displacements were separated into shear and bending components. Results showed that prior to cracking, overall stiffness as well as the individual components of stiffness are accurately predicted by mechanics of materials beam theory that accounts for shear deformation. Equivalent viscous damping ratios that were determined from the hysteretic energy before and after cracking were similar.     

Qualitative Identification of an Unknown Pesticide Using GC-MS and Online Resources

A senior-level instrumental analysis experiment is described in which students examine fruit for pesticide residues. This experiment involves fundamental instruction in sample preparation, the use of gas chromatography (GC) to resolve and deduce important components of a commercial pesticide preparation by matching against a certified standard, and unambiguous identification of the active pesticide by using mass spectrometry in conjunction with public data available on the Internet.     

Connecting mem-models with classical theories

A family of mem-models, including the mem-dashpots, mem-springs, and most recently, mem-inerters, is emerging as a new and powerful way of capturing complex nonlinear behaviors of materials and systems under various types of dynamic loads involving different frequency, amplitude, and loading histories (e.g., hysteresis). Under the framework of nonlinear state-space representation and hybrid dynamical systems, mem-springs may be formulated to effectively represent an inherent degradation of material state. It is shown in this study, for the first time, how the absement (time integral of strain/displacement), a signature state variable for a mem-spring, can be connected with the damage variable, a key quantity in continuum damage mechanics. The generalized momentum (time integral of stress), on the other hand, is shown to be efficient in modeling strain ratcheting via the concept of mem-dashpot. It is also shown in this study, for the first time, how two formulations of the memcapacitive system models (for mem-springs) are special cases of the Preisach model.

     

Organic electroluminescence using polymer networks from smectic liquid crystals

We report the synthesis of a red light-emitting and photopolymerizable smectic liquid crystal (reactive mesogen). We investigate the suitability of polymer networks formed from smectic reactive mesogens for use in organic light-emitting diodes (OLEDs). The use of mixtures of smectic reactive mesogens is shown to lower the processing temperature for the fabrication of OLEDs to room temperature. We also report efficient energy transfer from a nematic polymer network host to a smectic light-emitting dopant and polarized emission from a polymer network formed from an aligned smectic reactive mesogen.     

EXPERIMENTAL. MODAL. ANALYSIS OF REINFORCED CONCRETE STRUCTURES

Experimental modal analysis techniques have been shown to be applicable to both laboratory test specimens and in situ test structures made of reinforced concrete. These techniques, in general, apply only to linear structures; however, many concrete structures are designed to remain in the linear, uncracked response region during dynamic excitation (nuclear power plant structures, for example). Data from the experimental analyses agreed well with finite-element modal analysis results, and the numerical models were further refined based on the experimental results. Because of the relatively low excitation levels required, these methods provide engineers with techniques for assessing the as-built condition of a structure without introducing damage into the structure. If a concrete structure is damaged, the experimental modal analysis methods could possibly be used to monitor its deterioration.
Further investigations are needed to evaluate the sensitivity to damage of the experimentally determined modal properties. Also, methods must be found to determine, without prior modal data, if an in-situ structure is in a damaged state. These topics are being pursued by other researchers in the experimental modal analysis field.⁶
In its current form, experimental modal analysis methods can provide both practicing and research engineers with a valuable tool for verifying dynamic properties of reinforced concrete structures.