For Abstract see ChemInform Abstract in Full Text.
This chapter describes broadly the research performed in 2022 on high-nitrogen-content aromatic heterocycles. It encompasses a section devoted to azines (triazines, tetrazines, and heptazines) and a shorter section devoted to various heterocycles. Emphasis has been placed on the most significant and original works in all sections; a completely exhaustive account is beyond the scope of this report. The sections on s-triazines and s-tetrazines are the most important, given the interest of these compounds in the inverse Diels–Alder reaction and fluorescent molecules and materials. On the other hand, new heterocycles like g-triazines, a-triazines, a-tetrazines, and heptazines, which were almost absent only a decade ago, have come to a more and more important position, as have very recent applications like photocatalysis. An accurate account of these emerging families and applications has been duly included.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
This chapter covers work published in the calendar year 2021. The synthesis and reaction chemistry of six-membered heterocycles containing three or four nitrogen atoms and fused ring systems with three or more nitrogen atoms is reviewed.
Progress in the synthesis of seven-membered heterocycles bearing up to and including three N, O, or S heteroatoms continues unabated. The application of classical ring expansion strategies continues to be investigated. However, many original ring expansion approaches were also developed to synthesize these frameworks. Cyclization methodology remains a cornerstone in the construction of seven-membered heterocycles, with Dieckmann cyclizations, Friedel–Crafts alkylations and acylations, Pictet–Spengler-type and Bischler–Napieralski-type reactions, and ring-closing metatheses successfully deployed. Enabling cascade reactions and powerful catalytic processes continue to enhance access to seven-membered heterocycles. Total syntheses of natural products containing oxepane, azepane, and 1,3,6-oxadiazepane cores were completed. There was only one report of the preparation of a seven-membered ring containing four N, O, or S heteroatoms–a tricyclic tetrazepine.
Pyridines and benzo derivatives are important classes of heterocyclic compounds that have attracted significant attention due to their diverse chemical and biological properties. This review covers recent developments in the synthesis of these compounds during the year 2022, including new methods for functionalization and modification of their structures. It also highlights the potential of these compounds as versatile building blocks for the design of novel compounds with desired properties in various fields, including drug discovery, agrochemicals, materials science, and catalysis.
Saturated and aromatic heterocycles are present in polymers found in nature and those made synthetically. Saturated pyran and saturated furan ring systems are a major part of the backbone of naturally occurring polymers, polysaccharides, and nucleic acids, respectively. Synthetic heterocyclic polymers have been made mostly with aromatic heterocycles in the backbone and phenyl aromatics as the spacer units separating the heterocycles. Cycloaddition reactions (3 + 2 and 4 + 2) using alkynes and condensation reactions have been used in building the five- and six-membered heterocycles. Grafting a heterocyclic ring to the polymer backbone or its side chain has been done using vinyl heterocycles, nucleophilic addition, displacement reactions, and heterocyclic ring synthesis. The natural heterocyclic polymers are essential for human life, with major uses as food and in clothing. Synthetic heterocyclic polymers with excellent thermal, mechanical, and insulating properties have been useful in the aerospace, electronics, and chemical industries.
The chapter covers work published in the calendar year 2021. New methods for the ring synthesis of thiophenes, benzo[b]thiophenes, and selenophenes and tellurophenes are discussed. Novel reaction chemistry of thiophenes, benzo[b]thiophenes is covered. A selection of oligo- and polymeric thiophenes is briefly illustrated.
A fragment analysis was carried out, and the existing methods for the synthesis of 4,5,6,7-tetrahydroindoles published over the past 15 years were summarized, as well as, if and when necessary, an analysis was made of earlier works little known to a wide range of chemists. Particular attention is paid to fundamentally new methods that make it possible to synthesize various derivatives of the mentioned heterocyclic system from available and cheap reagents.
This chapter covers work published in the calendar year 2020. Novel reaction chemistry and new ring-synthetic methods for seven-membered heterocycles including azepines, benzoazepines, oxepines, thiepines, diazepines, benzodiazepines, dioxepines, and dithiepines are reviewed.
The review covers work published in the calendar year 2018 Novel reaction chemistry and new ring synthetic methods for thiophenes, thiophene oligomers, thiophene polymers, benzo[b]thiophenes, selenophenes, and tellurophenes, are reviewed..
This chapter reports on the different types of both monomeric and dimeric epi-3,6-dithio-2,5-diketopiperazines (ETPs). The ETP core chemical scaffold has been reported in over 100 natural products and their diverse antiviral, antifungal, antibacterial, and anticancer activities have attracted the interest of many researchers. Herein, we describe different examples and synthetic approaches attempted to obtain the ETP core structure, characterised by a diketopiperazine ring bridged by two (or more) sulfur atoms at the three and six positions.
