Chemistry of Heterocyclic Compounds最新文献

The conditions were developed and the optimal temperature regime was selected for a selective thionation of 5-aryl-3-[(dimethylamino)-methylidene]furan-2(3H)-ones with Lawesson's reagent. The stereochemistry of the synthesized 3-[(dimethylamino)methylidene]furan-2(3H)-thiones was established. Based on this, a number of 3-arylaminomethylidenefuran-2(3H)-thiones were synthesized via transamination reaction.

In this microreview, the application of noncatalyzed hetero-Diels–Alder reaction (formally [4+2] cycloaddition) with participation of conjugated nitroalkenes and their analogs for easy and selective preparation of 1,2-oxazine N-oxides was reviewed on the basis of recent publications. It was found that the best described processes are realized with full regioselectivity as well as at mild temperatures. It is interesting, that in some cases of the title reactions, the stepwise mechanism of the formation of the six-membered heterocyclic ring is more possible than classic one-step mechanism.

Background: Knee orthoses have been extensively used as a nonsurgical approach to improving knee deficiencies. Currently, arthritic knee conditions remain the leading cause of disability, and this number is expected to increase. As the use of knee orthoses varies widely, so has their effectiveness which is still largely debatable. Here, we present the functions and effectiveness of the three most prominent knee orthotic models dedicated to supporting knee osteoarthritis-unloader, patellofemoral, and knee sleeves.

Purpose/research question: Considering the depth and diversity of the many clinical studies and documented laboratory reports published to date, this literature review was created to educate the clinician, patient, and researcher on common knee orthoses used for the management of arthritic knee conditions. In doing so, we discuss their design, biomechanical effects, and clinical efficacy, as well as broader outcomes, limitations, and recommendations for use.

Results/synthesis: The knee orthoses discussed within the scope of this paper are dedicated to protecting the knee against strenuous compressive loads that may affect the patellofemoral and tibiofemoral joints of the knee. Since the knee has multiple axes of motion and articulating surfaces that experience different loads during functional activities, it can be implied that, to a large extent, knee brace designs can differ drastically. Unloader knee orthoses are designed to decrease tibiofemoral and patellofemoral joint pressures. Patellofemoral knee orthoses are designed to decrease strain on the patellofemoral and quadriceps tendons while stabilizing the patella. Knee sleeves are designed to stabilize movements, reduce pain in joints, and improve proprioception across the knee joint.

Conclusion: Although patients often report benefits from wearing braces, these benefits have not been confirmed by clinicians and scientific investigators. Results from these three orthosis types show that clinical efficacy is still elusive due to the different methodologies used by researchers.

Layman summary: Knee orthoses also referred to as knee brace are commonly used for support and stability of the knee. Unloader knee braces are designed to relieve and support those suffering from knee osteoarthritis by improving physical impairment and reducing pain. Patellofemoral knee braces aim to help patients manage patellofemoral pain syndrome. Rehabilitative compression sleeves, also known as knee sleeves, are often used to assist patients suffering from knee pain and laxity. Important findings on the three knee braces discussed show discrepancies in results. Their effectiveness and validity are yet to be understood.

The microreview covers the latest selected examples (2013–2024) on the synthesis and reactivity of [1, 2, 5]-thiadiazolo[3,4-b]pyridines and [1, 2, 5]selenadiazolo[3,4-b]pyridines. Their application is also discussed.

This microreview summarizes and analyzes literature for the years 2016–2023 on the construction of fluorophores based on benzo[g]coumarin backbone, which represent a push–pull system consisting of an annulated benzo and pyran rings. The main approaches to the synthesis of benzo[g]coumarins are condensation reactions, cyclization reactions, and pyran ring opening reactions followed by recyclization.

This microreview analyzes and summarizes the most recent advances in the synthesis of carbonyl-containing nitrofurans, including methods of nitration, oxidation, and esterification of the corresponding furan derivatives, published since 2017.

The review summarizes the methods of synthesis of pyrrolizidine (hexahydro-1H-pyrrolizine) derivatives published in the literature over the past five years. The methods can be conditionally divided into two major groups: synthesis from pyrrolidine derivatives and cyclization of acyclic precursors.

The microreview summarizes the methods of synthesis and studies of the properties of the derivatives of 1,2-dithiol condensed with a pyridine ring published in the literature over the last 10 years. The material is systematized according to the manner of coupling the [1,2]dithiolane system with the pyridine ring.

The present microreview systematizes recent advances in the synthetic approaches for novel thiazolo[4,5-b]-pyridines and summarizes pharmacological effects they were found to possess. In particular, modern synthetic techniques for thiazolo[4,5-b]pyridine bicyclic scaffold construction starting from thiazole or thiazolidine derivatives followed by pyridine annulation, which results in the target fused thiazolo[4,5-b]pyridines, are analyzed.

Urea and thiourea formed relatively stable liquid deep eutectic mixtures with KOH at certain ratios. These mixtures showed high activity in the reaction with benzils, quickly forming hydantoins and thiohydantoins in high yields.