Simple synthesis of 4-cyanoquinoline N-oxides

Nitroarenes and nitroalkenes as potential amino sources for the synthesis of N-heterocycles

Nitro-compounds are one of the cheapest and most readily available materials in the chemical industry and are commonly utilized as versatile building blocks. Previously, the synthesis of N-heterocycles was largely based on anilines. The utilization of nitroarenes and nitroalkenes for the synthesis of N-heterocyclic compounds can save at least one step, however, as compared to anilines. Thus, considerable attention has been paid to nitroarenes and nitroalkenes as new potential amino sources. Significant progress has been made in the reductive cyclization of nitroarenes or nitroalkenes to access various N-heterocycles in recent years. Herein, we comprehensively summarize the recent progress in the construction of N-heterocycles using nitroarenes and nitroalkenes as potential amino sources. The compatibility of the reaction substrate, its mechanism, applications, advantages, and limitations in this field are also discussed in detail.

Introduction of Carbon Substituents into Nitroarenes via Nucleophilic Substitution of Hydrogen: New Developments

Nucleophilic substitution of hydrogen in nitroarenes has become a powerful synthetic tool for functionalization of these important organic substrates, complementary to other modern methods. In this review we present new developments in the area of introduction of alkyl and functionalized alkyl substituents into nitroarene rings via nucleo­philic substitution of hydrogen, followed by application of these processes in the construction of carbo- and heterocyclic rings. Finally, new developments in the investigation of the mechanism of SNArH are summarized.

1 Introduction

2 Alkylation and Haloalkylation

3 Functionalized Carbon Substituents

4 Formation of Carbo- and Heterocyclic Rings

5 Mechanistic Aspects of SNArH

6 Conclusion

Facile Fabrication of Hierarchical MOF-Metal Nanoparticle Tandem Catalysts for the Synthesis of Bioactive Molecules

Multifunctional metal-organic frameworks (MOFs) that possess permanent porosity are promising catalysts in organic transformation. Herein, we report the construction of a hierarchical MOF functionalized with basic aliphatic amine groups and polyvinylpyrrolidone-capped platinum nanoparticles (Pt NPs). The postsynthetic covalent modification of organic ligands increases basic site density in the MOF and simultaneously introduces mesopores to create a hierarchically porous structure. The multifunctional MOF is capable of catalyzing a sequential Knoevenagel condensation-hydrogenation-intramolecular cyclization reaction. The unique selective reduction of the nitro group to intermediate hydroxylamine by Pt NPs supported on MOF followed by intramolecular cyclization with a cyano group affords an excellent yield (up to 92%) to the uncommon quinoline N-oxides over quinolines. The hierarchical MOF and polyvinylpyrrolidone capping agent on Pt NPs synergistically facilitate the enrichment of substrates and thus lead to high activity in the reduction-intramolecular cyclization reaction. The bioactivity assay indicates that the synthesized quinoline N-oxides evidently inhibit the proliferation of lung cancer cells. Our findings demonstrate the feasibility of MOF-catalyzed direct synthesis of bioactive molecules from readily available compounds under mild conditions.

Transition-metal-free synthesis of 3-(1-pyrrolidinyl)quinolines and 3-(1-pyrrolidinyl)quinoline 1-oxides via a one-pot reaction of 3-(1-pyrrolidinyl)crotonates with nitrobenzenes

A carbanion of tert-butyl 3-(1-pyrrolidinyl)crotonate adds to nitrobenzenes to form σ^H-adducts, which in the presence of pivaloyl chloride and triethylamine are converted into 3-(1-pyrrolidinyl)quinolines or 3-(1-pyrrolidinyl)quinoline 1-oxides depending on the nitrobenzene structure. This is the first methodology in which a quinoline ring is constructed from a substrate bearing a pyrrolidinyl ring. Starting from optically pure enamines, the method allows synthesis of the corresponding chiral products without racemisation.