Assembly of Furazan-Fused Quinolines via an Expeditious Metal-Free [2+2+1] Radical Tandem Cyclization Process

Preparation of a benziodazole-type iodine(III) compound and its application as a nitrating reagent for synthesis of furazans via a copper-catalyzed cascade process

The existing hypervalent I(III) reagents bearing ONO2 group are limited in types and their applications primarily focused on the nitrooxylation reactions featuring a fully-exo fashion. Herein, a benziodazole-type O2NO-I(III) compound was prepared and its reaction with β-monosubstituted enamines in the presence of CuI could trigger a radical nitration/cyclization/dehydration cascade to provide a series of less explored but biologically interesting furazan heterocycles. Mechanistically, the benziodazole-type O2NO-I(III) compound acts as a nitrating reagent and incorporates its NO moiety into the final furazan product in a fully-endo model, a process of which was proposed to involve nitration, cyclization and dehydration.

Cascade Annulation Strategy for Expeditious Assembly of Hydroxybenzo[c]chromen-6-ones and Their Photophysical Property Studies

A 1,8-diazabicyclo[5.4.0]undec-7-ene-promoted cascade double-annulation of ortho-alkynyl quinone methide (in situ generated from modular propargylamine) for constructing of 2-aryl-4-hydroxybenzo[c]chromen-6-ones is developed. This synthetic strategy offers remarkable operational simplicity as it allows the use of benchtop-grade solvents without the need for predrying measures and inert atmosphere protection. Additionally, it demonstrates good functional group compatibility. The photophysical properties of these compounds were also examined, revealing bright fluorescence with high quantum yields.

Synthetic approaches and applications of an underprivileged 1,2,5-oxadiazole moiety: A review

1,2,5-oxadiazole belongs to five-membered heterocyclic compounds with two nitrogen and one oxygen atom. In comparison with other heterocyclic moieties, 1,2,5-oxadiazoles moiety is considered as underprivileged as it attracted little attention of the researchers although lot of scopes and possible applications in medicinal, material and agriculture science. 1,2,5-oxadiazole and its derivatives have been reported as good pharmacophores as carbonic anhydrase inhibitors, antibacterial, vasodilating agents, antimalarial, anticancer, etc. In the presented manuscript, we reviewed granted patents and different synthetic strategies which have been reported for the synthesis of 1,2,5-oxadiazoles such as cycloaddition, dimerization, cyclodehydration, condensation, thermolysis, nitration, oxidation and ring-conversion. These synthetic methods have also been analysed for their merits and demerits. The manuscript also highlighted various applications of 1,2,5-oxadiazole and its derivatives. We hope that researchers across the scientific streams will be benefitted from the presented review articles for designing their work related to 1,2,5-oxadiazoles.

TBN-triggered, manipulable annulations of o-hydroxyarylenaminones for divergent syntheses of oximinochromanones and oximinocoumaranones

Divergent synthesis provides an indispensable route to rapid acquisition of structurally diverse chemical scaffolds from identical starting materials. Herein, we describe unprecedented divergent annulations of o-hydroxyarylenaminones promoted by tert-butyl nitrite (TBN) under mild conditions. Two different types of benzo-oxa-heterocycle, including oximinochromanones and oximinocoumaranones, were smoothly assembled with a broad substrate scope and good functional group compatibility.