Current Organic Chemistry - Volume 25, Issue 15, 2021

The spices of Pinus, the most widespread genus of the Pinaceae family in the northern hemisphere, often have sparse understory vegetation. However, sunlight intensity on the pine forest floor is sufficient for undergrowth. Allelopathy, therefore, is considered to be involved in the formation of sparse understory vegetation. The evidence for the allelopathy of several pine species has accumulated in the literature over the decades. Extracts of pine needle- like leaves, roots, litter, and soil under pine trees suppressed several plant species, including undergrowth plant species of pine forests. A substantial number of secondary metabolites such as terpenoids, phenolics, cinnamic acids, carboxylic acids, fatty acids, and flavonoids have been identified in pine needles and roots, litter and soil under pine trees. The evidence also suggests that some of these compounds are probably released into the soil through the decomposition of the plant litter, and into the surrounding environment as volatiles. The most active compounds found in the pine soil were methyl 15-hydroxy-7-oxodehydroabietate and 7-oxodehydroabietic acid; both compounds may also be formed through the degradation of resin acids, which were found abundantly in pine trees. Bioactive compounds released into the soil and surrounding environment possibly act as allelochemicals and suppress the invasion of undergrowth plants into the forests, resulting in the establishment of the sparse understory vegetation. The paper summarized the allelopathic activity of 16 Pinus species and 38 allelochamicals.

Cyanine Dyes (CD) are a functional class of organic molecules used in several applications ranging from photography to bioimaging. Most well-known features of CDs reside on high molar extinction coefficients up to 105 L mol-1cm-1 and on the absorption spectra, ranging from 500 to 1000 nm, which can be fine-tuned both by extending the length of the central methylene bridge or by modulating the terminal heterocycles. In the last decades, new synthetic methodologies, namely microwave-assisted and the solid-phase procedure, have been developed to overcome the limitation of the classical synthetic protocols. While the microwave approach usually reduces the exposure time of the reagents and products to thermal degradation, the solid-phase methodology allows easier synthetic protocols, which are translated into higher yields and simpler products purification. In the present review, a comprehensive analysis of the solid-phase methods for the synthesis of asymmetrical CDs is discussed, with a critical evaluation of the difference among the currently available solid-state approaches.

Oxazole-containing compounds have diverse biological activities, such as antimicrobial, anticancer, antitubercular, anti­inflammatory, antidiabetic, antiobesity, antimalarial, and antiviral activities, and some of them have been used as drugs for treating diseases. They also play important roles in the synthesis of bioactive natural products, pharmaceuticals and synthetic transformations as well as in materials, catalyst and agriculture fields. Thus, the development of more efficient and facile synthetic approaches to access oxazole compounds has attracted the intensive interest of chemists, and diverse methods for their synthesis have been investigated. Various established methods have been improved and modified, while numerous novel methods have been discovered. This article will summarize considerable studies on the construction of the oxazole skeleton which date back to 2014.

Toluene and its derivatives have been well established as versatile scaffolds in organic synthesis over the last few decades. This review provides a brief and concise overview of the current status and latest methodologies in the synthetic utility of toluene and its derivatives by exploiting both the alkyl-sp³ and aryl-sp² carbons via C-H activation. The review also explores the effect of various substituents on the toluene derivatives in facilitating different reactions.

Glutathione (GSH), due to the ability to capture the reactive electrophiles of exoand endogenous origins, is expected to prevent cross-linking induced by these compounds. However, it may instead become cross-linked itself. We subjected glutathione to reactions with model α,β-unsaturated carbonyl systems resulting from the interactions of adenosine with bifunctional aldehyde products of lipid peroxidation, and identified a range of adducts and cross-linked products. We found that the S-conjugated adducts, initially formed in the typical GSH Michael addition to α,β-unsaturated carbonyl system, unexpectedly undergo gradual degradation giving rise to the final N-conjugated products, in which formation of peptide amino group is involved instead of sulfhydryl functionality. This finding shows that the role of the GSH amino group in the non-enzymatic detoxification is underestimated, and that reactions between cellular α,β-unsaturated carbonyl compounds and GSH may be more complex than are presently perceived.