Organocatalytic Synthesis of Highly Functionalized Pyridines at Room Temperature

Organocatalyzed oxidative N-annulation for diverse and polyfunctionalized pyridines

A variety of polyfunctionalized pyridines were synthesized from readily available ketones with α,β-unsaturated aldehydes and ammonium acetate under a mild organocatalyst.

Silver(i)–N-heterocyclic carbene catalyzed multicomponent reactions: a facile synthesis of multisubstituted pyridines

A room temperature four component reaction between aromatic aldehydes, CH₂(CN)₂and NH₄OAc with ketones mediated by Ag(i)–NHC pre-catalysts to produce multisubstituted pyridines in a short reaction time in eco-friendly ethanol was described.

Transition-metal-free synthesis of substituted pyridines via ring expansion of 2-allyl-2H-azirines

A new strategy to open the 2-allyl-2H-azirines by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) promotion in metal-free conditions affording 1-azatrienes that in situ electrocyclize to the pyridines in good to excellent yields is reported. The reaction displays a broad substrate scope and good tolerance to a variety of substituents including aryl, alkyl, and heterocyclic groups. In addition, one-pot synthesis of pyridines from oximes via in situ formation of 2H-azirines was achieved.

Organocatalysis: Key Trends in Green Synthetic Chemistry, Challenges, Scope towards Heterogenization, and Importance from Research and Industrial Point of View

This paper purports to review catalysis, particularly the organocatalysis and its origin, key trends, challenges, examples, scope, and importance. The definition of organocatalyst corresponds to a low molecular weight organic molecule which in stoichiometric amounts catalyzes a chemical reaction. In this review, the use of the term heterogenized organocatalyst will be exclusively confined to a catalytic system containing an organic molecule immobilized onto some sort of support material and is responsible for accelerating a chemical reaction. Firstly, a brief description of the field is provided putting it in a green and sustainable perspective of chemistry. Next, research findings on the use of organocatalysts on various inorganic supports including nano(porous)materials, nanoparticles, silica, and zeolite/zeolitic materials are scrutinized in brief. Then future scope, research directions, and academic and industrial applications will be outlined. A succinct account will summarize some of the research and developments in the field. This review tries to bring many outstanding researches together and shows the vitality of the organocatalysis through several aspects.

A catalyst-controlled selective synthesis of pyridines and pyrroles

We have developed a dual reaction manifold that enables the selective synthesis of both pyridines and pyrroles from the common substrates α-diazo oxime ethers.

Metal-free synthesis of substituted pyridines from aldehydes and NH4OAc under air

A metal-free and efficient method for the synthesis of substituted pyridines with aldehydes and NH₄OAc under mild conditions using air as the oxidant was developed.

Access to pyridines via DMAP-catalyzed activation of α-chloro acetic ester to react with unsaturated imines

Facile access to trisubstituted pyridines from α-chloro acetic ester and unsaturated imines is achieved.

Isothiourea-mediated one-pot synthesis of functionalized pyridines

Acids to bases: The synthesis of 2,4,6-trisubstituted pyridines from (phenylthio)acetic acid and a range of α,β-unsaturated ketimines is reported. This process proceeds by intermolecular Michael addition/lactamization, thiophenol elimination, and N- to O-sulfonyl migration, giving 2-sulfonate-substituted pyridines which are readily derivatized to generate structural diversity.