Isomerization of Ninhydrin-Heterocyclic Ketene Aminal Adducts: Kinetic versus Thermodynamic Control, Solvent Dependency and Mechanism

One-pot synthesis of dihydro-8H acenaphtho[1',2':4,5]pyrrolo[1,2-a]imidazole-diol derivatives

A simple and efficient method for the synthesis of dihydro-8H-acenaphtho[1',2':4,5]pyrrolo[1,2-a]imidazole-diol derivatives via one-pot, four-component reaction of 1,1-bis(methylthio)-2-nitroethene, various amines, and acenaphthoquinone was developed. All the reactions were carried out in ethanol at reflux without any catalyst. The main advantages of this method are good to high yields, experimental simplicity, mild reaction conditions, simple workup, and easy purification.

Cascade process for direct synthesis of indeno[1,2-b]furans and indeno[1,2-b]pyrroles from diketene and ninhydrin

Novel and efficient multicomponent reactions (MCRs) involving diketene, ninhydrin (indane-1,2,3-trione) and one primary amine (3CR) or two different primary amines (4CR) were achieved for the successful synthesis of dihydro-4H-indeno[1,2-b]furan-3-carboxamides or tetrahydroindeno[1,2-b]pyrrole-3-carboxamides, respectively. The merits of this method are highlighted by using either commercially available or easily accessible starting materials, operational simplicity, facile workup procedure, efficient usage of all the reactants, tolerance of a variety of functional groups and ability to conduct under un-catalyzed reaction condition. The products were also isolated by just decantation of the solvent, and for the purification column chromatography was non-required.

NitroketeneN,S-acetals: synergistic building blocks for the synthesis of heterocycles

The development of novel heterocyclic compounds from simple and easily accessible starting components is of significant importance in medicinal chemistry. Due to the presence of active chromophores and potent pharmacological activities, nitroketene N,S-acetals have emerged as a fascinating building block in organic synthesis. The synergistic skeleton of these acetals and the presence of electron-donating as well as electron-withdrawing groups lead to the generation of distinctive structural features and are highly useful for building diverse heterocyclic rings. This review highlights the preparation of different nitroketene N,S-acetals and their applications in the synthesis of diverse heterocyclic compounds.

This review highlights the synthesis of several kinds of nitroketene N,S-acetals and their applications in the synthesis of different kinds of heterocyclic compounds.

Access to indenofurans and indenopyridines via annulation of heterocyclic ketene aminals, o-phthalaldehyde and cyclic 1,3-diketones

Access of indenofurans and indenopyridines through a one pot, three-component protocol.

Tetrahydroindeno[1',2':4,5]pyrrolo[1,2-a]imidazol-5(1H)-ones as novel neonicotinoid insecticides: reaction selectivity and substituent effects on the activity level

Tetraheterocyclic tetrahydroindeno[1',2':4,5]pyrrolo[1,2-a]imidazol-5(1H)-one derivatives as novel neonicotinoid candidates were designed and prepared by selective etherification, chlorination and esterification of ninhydrin-heterocyclic ketene aminals adducts. Some of the designed compounds showed excellent insecticidal activity against cowpea aphids (Aphis craccivora), brown planthopper (Nilaparvata lugens), and armyworm (Mythimna separata). In particular, the activity against armyworm (Mythimna separata) improved a lot in contrast with that of imidacloprid and cycloxaprid. The research here provides a novel neonicotinoid chemotype for further development.