"Super stable" Blatter radicals through ArLi addition: surprising chemistry of 7-(trifluoromethyl)benzo[e][1,2,4]triazine

Addition of PhLi to 7-(CF₃)benzo[e][1,2,4]triazine at -78 °C gives the "super stable" Blatter radical in high yields, while above -5 °C two additional products are formed. XRD analysis revealed the formation of a "trimer" and a benzo[f][1,2,4]triazepine via a novel mechanism. The latter is formed from the anion generated from the isolated radical, which suggests its instability in organic batteries.

Chemical synthesis in competition with global genome mining and heterologous expression for the preparation of dimeric tryptophan-derived 2,5-dioxopiperazines

Covering: up to the end of 2021Within the 2,5-dioxopiperazines-containing natural products, those generated from tryptophan allow further structural diversification due to the rich chemical reactivity of the indole heterocycle. The great variety of natural products, ranging from simple dimeric bispyrrolidinoindoline dioxopiperazines and tryptophan-derived dioxopiperazine/pyrrolidinoindoline dioxopiperazine analogs to complex polycyclic downstream metabolites containing transannular connections between the subunits, will be covered. These natural products are constructed by Nature using hybrid polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) assembly lines. Mining of microbial genome sequences has more recently allowed the study of the metabolic routes and the discovery of their hidden biosynthetic potential. The competition (ideally, also the combined efforts) between their isolation from the cultures of the producing microorganisms after global genome mining and heterologous expression and the synthetic campaigns, has more recently allowed the successful generation and structural confirmation of these natural products. Their biological activities as well as their proposed biogenetic routes and computational studies on biogenesis will also be covered.

Total Synthesis of Homo- and Heterodimeric Bispyrrolidinoindoline Dioxopiperazine Natural Products

Total synthesis and structural confirmation of homo- and heterodimeric bispyrrolidinoindoline dioxopiperazine alkaloids isolated from fungi and bacteria, namely, ditryptoleucine A, ditryptoleucine B (11), the N,N'-bis-demethylated analogue (+)-12, (-)-dibrevianamide F (13), (-)-SF-5280-451 (14), tetratryptomycin A (15), (-)-tryprophenaline (17), and (-)-SF-5280-415 (18), has been carried out starting from the corresponding bispyrrolidinoindolines derived from tryptophan. Our efforts to synthesize all possible diastereomers of the natural ditryptoleucine isolates uncovered structural factors that determine the rate and efficiency of dioxopiperazine ring formation, leading in some cases to mixtures of diastereomers by concomitant epimerization, to the formation of their putative monomeric dioxopiperazine dipeptide biogenetic precursors, and to the alternative formation of a dimer with a fused 1,3,5-triazepan-6-one heterocycle.

New triazepine carboxylate derivatives: correlation between corrosion inhibition property and chemical structure

In this investigation, attempts have been made to study the corrosion inhibition properties of three new triazepine carboxylate compounds for mild steel in 1.0 M hydrochloric acid medium. The evaluation was carried out using mass loss, electrochemical impedance spectroscopy and polarization curves measurement. Impedance diagrams and Bode plots for uninhibited and inhibited systems were analyzed using Zview program. The fitted data observed trails in nearly the same pattern as the experimental results. It is showed that triazepine carboxylate compounds are very good inhibitors for mild steel corrosion in 1.0 M hydrochloric acid medium which act as mixed-type inhibitors. So, the inhibition efficiency was increased with inhibitor concentration in the order Cl–Me–CN > Me–CN > Cl–Me–CO2Et which depended on their molecular structures. Electrochemical impedance spectroscopy showed that all compounds act by the formation of a protective film at the metal surface. Surface analyses via SEM and Optical 3D profilometry were used to investigate the morphology of the steels before and after immersion in 1.0 M HCl solution containing inhibitors. The correspondence between inhibition property and molecular structure of the triazepine carboxylate compounds was investigated, using density functional theory (DFT). Experimental and DFT study was further supported by molecular dynamic simulations study.

Bicyclic 6 + 6 systems: the chemistry of pyrimido[4,5-d]pyrimidines and pyrimido[5,4-d]pyrimidines

The present study provides an overview of the chemistry and biological significance of pyrimido[4,5-d]pyrimidine and pyrimido[5,4-d]pyrimidine analogs as types of bicyclic [6 + 6] systems. The main sections include: (1) synthesis methods; (2) the reactivities of the substituents linked to the ring carbon and nitrogen atoms; and (3) biological applications. A discussion demonstrating the proposed mechanisms of unexpected synthetic routes is intended. The aim of this study is to discuss the synthetic significance of the titled compounds and to establish the biological characteristics of this class of compounds as studied to date, where the compounds have been applied on a large scale in the medical and pharmaceutical fields. This survey will help researchers in the fields of synthetic organic and medicinal chemistry to undertake and improve new approaches for the construction of new standard biological components.

Cyclocondensation reactions of an electron deactivated 2-aminophenyl tethered imidazole with mono/1,2-biselectrophiles: synthesis and DFT studies on the rationalisation of imidazo[1,2-a]quinoxaline versus benzo[f]imidazo[1,5-a][1,3,5]triazepine selectivity switches

Microwave-assisted cyclocondensation of title compounds afforded unreported imidazo[1,2-a] quinoxaline and benzo[f]imidazo[1,5-a][1,3,5]triazepines in high yields.