Facile synthesis of substituted pyrrole-fused isocoumarins from ninhydrin

Silica–sulfuric acid and alumina–sulfuric acid: versatile supported Brønsted acid catalysts

–SO3H functionalized silica and alumina have emerged as efficient and eco-compatible heterogeneous solid acid catalysts for the construction of various important molecular skeletons.

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.

Synthesis of 5H-spiro[furan-2,2′-indene]-1′,3′,5-triones from tetrahydro-4-oxoindeno[1,2-b]pyrroles

A simple approach to assembling of functionalized spiro-butenolide-indenetriones from oxoindeno[1,2-b]pyrrole derivatives in the presence of H2SO4 is described. Simplicity of the procedure, short reaction time and excellent yields are important features of this protocol.

3-Hy-droxy-2-phenyl-2,3,3a,7a-tetra-hydro-1H,5H-pyrano[3,2-b]pyrrol-5-one: crystal structure and Hirshfeld surface analysis

The title isoaltholactone derivative, C13H13NO3, has an NH group in place of the ether-O atom in the five-membered ring of the natural product. The five-membered ring is twisted about the N-C bond linking it to the six-membered ring, which has a half-chair conformation with the O atom connected to the ether-O atom lying above the plane defined by the remaining atoms. The dihedral angle between the mean planes of the rings comprising the fused-ring system is 75.10 (8)°. In the crystal, hy-droxy-O-H⋯N(amine) hydrogen bonding sustains linear supra-molecular chains along the a axis. Chains are linked into a three-dimensional architecture via amine-N-H⋯π(phen-yl) and phenyl-C-H⋯O(hy-droxy) inter-actions. The influence of the amine-N-H⋯π(phen-yl) contact on the mol-ecular packing is revealed by an analysis of the Hirshfeld surface.

Developments toward the synthesis and application of 3-hydroxyindanones

3-Hydroxyindanone is an important scaffold in many natural products, biologically active compounds, and functional materials. This review provides a comprehensive overview of the construction of 3-hydroxyindanone derivatives and their applications towards pharmaceutically promising drug candidates.

Synthesis of a new class of pyrazole embedded spirocyclic scaffolds using magnetically separable Fe3O4@SiO2–SO3H nanoparticles as recyclable solid acid support

A green methodology for the synthesis of a new class of pyrazole embedded spirocyclic scaffolds has been developed using Fe₃O₄@SiO₂–SO₃H magnetic nanoparticles.

Synthesis of 4-hydroxyindole fused isocoumarin derivatives and their fluorescence “Turn-off” sensing of Cu(ii) and Fe(iii) ions

A simple and efficient protocol has been developed for the synthesis of 4-hydroxyindole fused isocoumarins from easily available starting materials.

Fluorescent and antioxidant studies of effectively synthesized isochromenopyrrolone analogues

An efficient strategy for the synthesis of 3-acetyl-2-methyl-1-phenylisochromeno [4,3-b] pyrrol-5(1H)-ones 4a–f have been developed using montmorillonite K10 as a catalyst. The synthesized compounds have prominent antioxidant activity and fluorescence properties.

Facile cyclization in the synthesis of highly fused diaza cyclooctanoid compounds using retrievable nano magnetite-supported sulfonic acid catalyst

Magnetically separable Fe₃O₄–SO₃H nano particles have been prepared and established as an efficient catalyst for the synthesis of dihydrofuran fused cyclooctanoids via the dehydration reaction of dihydroxy cyclooctanoid heterocylces.

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

A convenient and efficient methodology for the synthesis of densely substituted pyrrole-fused isocoumarins, which employs solid-supported silica sulfuric acid (SSA) as catalyst, has been developed. When the mixture of ninhydrin adducts of acetylacetone/ethyl acetoacetate and primary amines was heated on the solid surface of SSA under solvent-free conditions, the pyrrole-fused isocoumarins were formed in good yields. This synthetic method has several advantages such as the employment of solvent-free reaction conditions without the use of any toxic reagents and metal catalysts, the ease of product isolation, the use of a recyclable catalyst, the low cost, the easy availability of the starting materials, and the excellent yields of products.