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The skeletal editing of azaarenes through insertion, deletion, or swapping of single atoms has recently gained considerable momentum in chemical synthesis. Here, we describe a practical skeletal editing strategy using vinylcarbenes in situ generated from trifluoromethyl vinyl N‐triftosylhydrazones, leading to the first dearomative skeletal editing of pyrroles through carbon‐atom insertion. Furthermore, depending on the used catalyst and substrate, three types of peripheral editing reactions of pyrroles are also disclosed: α‐ or γ‐selective C−H insertion, and [3+2] cycloaddition. These controllable molecular editing reactions provide a powerful platform for accessing medicinally relevant CF3‐containing N‐heterocyclic frameworks, such as 2,5‐dihydropyridines, piperidines, azabicyclo[3.3.0]octadienes, and allylated pyrroles from readily available pyrroles. Mechanistic insights from experiments and density functional theory (DFT) calculations shed light on the origin of substrate‐ or catalyst‐controlled chemo‐ and regioselectivity as well as the reaction mechanism. [ABSTRACT FROM AUTHOR]

Herein, we wish to report the scandium triflate catalyzed synthesis of novel dibenzo[ b,f ][1,5]oxazocin-6-ones in PEG-400 as a greener medium. Using this simple and greener protocol, for the very first time we have constructed novel eight-membered heterocyclic compounds in good yields. The PEG-Sc(OTf) 3 catalytic system can be reused for four consecutive runs without any significant loss of its catalytic activity. [ABSTRACT FROM AUTHOR]

In this communication, for the first time we have constructed a series of novel azo group fused 2 H -chromene-3-carboxylate and 3-acetyl-2 H -chromene derivatives via the Knoevenagel condensation reaction of active methylene compounds with aromatic 5-arylazosalicylaldehydes followed by a nucleophilic addition of the phenolic hydroxyl group to the carbonyl group of one of the ester groups. Shorter reaction times, high yields, simple work-up procedure and mild reaction conditions are the advantages of the present method. In addition, we have also studied the antioxidant activities using DPPH, hydroxyl, and ABTS radical scavenging methods. [ABSTRACT FROM AUTHOR]

Ordered mesoporous silica material MCM-41 with covalently anchored boric acid groups located inside the mesochannels has been utilized as an acid catalyst for the 'green' synthesis of 2-aryl-2,3-dihydroquinazolin-4(1 H)-one derivatives under solvent-free condition. This novel synthetic method offers advantages, such as excellent yields, simple reaction procedure, short reaction times and mild reaction conditions. [ABSTRACT FROM AUTHOR]

In this Letter we wish to report a simple and efficient synthetic protocol for the synthesis of 5-substituted 1 H -tetrazole derivatives through the [2+3] cycloaddition of nitriles with sodium azide using ceric ammonium nitrate supported HY-zeolite as a novel catalyst. Excellent yields of the corresponding tetrazoles were obtained through this cost-effective protocol under aerobic conditions with shorter reaction time under mild reaction conditions. [ABSTRACT FROM AUTHOR]

The title chromenes are efficiently prepared by Knoevenagel condensation of active methylene compounds with aromatic azosalicylaldehydes using piperidine as catalyst followed by nucleophilic addition of the phenolic hydroxyl group to the carbonyl group of one of the ester groups. [ABSTRACT FROM AUTHOR]

via condensation of dimedone with aromatic aldehydes (13 examples) [ABSTRACT FROM AUTHOR]