π-Extended Pyrrole-Fused Heteropine: Synthesis,Properties, and Application in Organic Field-Effect Transistors

Sulfur-embedded polycyclic aromatic compounds have been used as building blocks for numerous organic semiconductors over the past few decades. While the success is based on thiophene-containing compounds, aromatic compounds that contain thiepine, a sulfur-containing seven-membered-ring arene, has been less well investigated. Here we report the synthesis and properties of π-extended pyrrole-fused heteropine compounds such as thiepine and oxepine. A π-extended pyrrole-fused thiepine exhibited a “pitched π-stacking” structure in the crystal, and exhibited a high charge carrier mobility of up to 1.0 cm² V⁻¹ s⁻¹ in single-crystal field-effect transistors.     

Synthesis of functionalized pyrroles and fused pyrroles through intermolecular [3 + 2] cycloaddition reaction

A facile and efficient synthesis of pyrrole and pyrrole-fused heterocyclic compounds has been demonstrated. The current protocol involves the in situ generation of azomethine ylides which undergoes intermolecular cycloaddition reaction and subsequent treatment with DDQ provides the pyrrole and fused heterocyclic compounds in good yields.     

Simple and Convenient Synthesis of 4‐Unsubstituted‐3‐(3‐Oxoalkyl)isocoumarins

A simple transformation of 2‐alkylfurans and 2‐formylbenzoic acids into 4‐unsubstituted 3‐(3‐oxoalkyl)isocoumarins is described. It is based on the synthesis of 2‐(2‐carboxybenzyl)furans followed by their acid‐catalyzed recyclization to the target isocoumarins.     

Preparation of fused 1,3-oxazine-2,4-diones as potential antitumor agents

A series of indole, thiophene and pyrrole-fused 1,3-oxazine-2,4-diones, 2-methyl-1,3-oxazin-4-ones and 2-dimethylamino-1,3-oxazin-4-ones were synthesized and evaluated as antitumor agents.     

An expeditious and environmentally friendly synthesis of 3-substituted isocoumarins using microwave irradiation

A microwave-assisted, environmentally friendly, high-yielding, time-saving synthesis of medicinally important 3-substituted isocoumarins was carried out in a single step by direct condensation of homophthalic acid with aryol and acyl chlorides under solvent-free conditions without any solid support. The synthesised isocoumarins were structurally characterised by microanalysis, 1H NMR, EI, IR and UV.     

An efficient synthesis of isocoumarins via a CuI catalyzed cascade reaction process

3-Alkyl isocoumarins are provided by CuI/amino acid-catalyzed Sonogashira coupling reaction of o-bromo benzoic acids and terminal alkynes and the subsequent additive cyclization. This cascade process allows synthesis of diverse isocoumarins by varying both coupling partners bearing a wide range of functional groups.     

Differentiation inducing activities of isocoumarins from Hydrangea Dulcis Folium

In the course of searching for differentiation inducers against leukemic cells from plants, we have recognized the differentiation inducing activities of the methanolic extract of Hydrangea Dulcis Folium. Activity guided separation of the extract was carried out using M1 cells, and seven isocoumarins were isolated as active substances. These isocoumarins showed the activities at the concentration of 100 microM and non-cytotoxic effects even at 300 microM.     

Regioselective cyclization of 2-alkynylbenzoic acid in water for the synthesis of isocoumarin

In this work, a regioselective synthesis of isocoumarins from 2-alkynylbenzoic acid is reported. The transformations proceed smoothly with good yields in water via a metal-free radical pathway. When catalytic TBAB is employed, the reaction provides various isocoumarin derivatives according to the structures of the corresponding precursors. It is believed that TBAB serves as a phase transfer catalyst and radical initiator in the reaction. Compared to previous methodologies, the synthetic procedure reported herein provides a more environmentally benign route for the synthesis of isocoumarins.     

Rh(III)-catalyzed C-H activation of primary benzamides and tandem cyclization with cyclic 2-diazo-1,3-diketones for the synthesis of isocoumarins

A simple and efficient Rh(III)-catalyzed C-H activation and tandem intramolecular cyclization for the synthesis of isocoumarins has been developed. The protocol uses easily available primary benzamides and cyclic 2-diazo-1,3-diketones as starting materials. This reaction proceeds via C-C and C-O bond formation in a single reaction vessel, and the corresponding isocoumarins were obtained in moderate to excellent yields (58%–97%). The well established protocol showed high functional group tolerance, which provided an efficient and alternative route to isocoumarin backbone.     

Synthesis of Some 3‐Substituted Isochromen‐1‐ones

An alternative method for the synthesis of 3‐substituted isocoumarins from homophthalic acid and ester is described.     

Synthesis of 3-substituted isocoumarins and their inhibitory effects on degranulation of RBL-2H3 cells induced by antigen

Eleven 3-substituted isocoumarins and a benzylidenephthalide were synthesized through thermal cyclization reaction of delta- and gamma-ketoamides, respectively. Subsequent deprotection of the hydroxyl groups of the resulting isocoumarin and benzylidenephthalide compounds afforded thunberginols A, B, and F, respectively, which originated from the processed leaves of Hydrangea macrophylla SERINGE var. thunbergii MAKINO. The synthesized isocoumarins and thunberginols were evaluated for their anti-allergic activity, in which thunberginol B exhibited the highest inhibitory potency on the degranulation of RBL-2H3 cells induced by antigen. Structure-activity relationship studies were carried out to determine the necessary substituents on the 3-phenylisocoumarin skeleton for inhibitory activity.     

One-pot synthesis of pyrrolo[3,2-d]pyridazines and pyrrole-2,3-diones via zirconocene-mediated four-component coupling of Si-tethered diyne, nitriles, and azide

A one-pot synthesis of pyrrolo[3,2-d]pyridazine derivatives via zirconocene-mediated four-component coupling of one Si-tethered diyne, two nitriles, and one azide is reported. When TMSN(3) was used, pyrrole-2,3-diones were formed in good yields. Further condensation of these highly functionalized pyrrole-2,3-diones with hydrazine and hydroxylamine afforded useful pyrrole-fused heterocycles.     

The reaction between phloroglucinol and vic polycarbonyl compounds: extension and mechanistic elucidation of Kim's synthesis for bipolarofacial bowl-shaped compounds

Kim's serendipitous synthesis of a novel cavitand by the one-pot reaction between phloroglucinol and ninhydrin was revisited and extended. A much deeper cavitand was obtained by replacing ninhydrin with benzo[f]ninhydrin. Performing the reaction in a stepwise manner, employing both ninhydrin and benzo[f]ninhydrin, provided ‘mixed bowls’ of lower symmetry. Other cyclic polyketones, such as 1,2-indanedione and alloxan, form with phloroglucinol only partially closed structures. Crystallographic studies of the intermediate compounds in this reaction confirm Kim's postulate that the bowl formation involves hemiketal ring-openings and rearrangements.     

Isocoumarin Thioanalogues as Potential Antibacterial Agents

A series of 3-substituted-1H-isochromene-1-thiones (3) were prepared by the reaction of 3-substituted isocoumarins (2) with Lawesson's reagent in the presence of toluene under a nitrogen atmosphere. The antimicrobial activities of the newly synthesized products were measured using Gram-negative (Escherichia coli, Salmonella typhi, and Proteus mirabilis) and Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus). Synthesized thioanalogue of isocoumarins showed good antibacterial activity against Proteus mirabilis.     

Synthetic Routes to Ninhydrins. Preparation of Ninhydrin, 5-Methoxyninhydrin,and 5-(Methylthio)Ninhydrin

Two syntheses of 5-methoxyninhydrin (2,2-dihydroxy-5-methoxy-1,3-indanedione) are described. One method employs a novel and efficient two step route, which begins with commercially available 6-methoxy-1-indanone. The application of this strategy for the preparation of a new ninhydrin derivative, 5-(methylthio)ninhydrin, and ninhydrin is also presented.     

Efficient synthesis of aminomethylated azaindoles and corresponding pyrrole-fused derivatives by copper-catalyzed domino multicomponent coupling and cyclization

Efficient methods for the synthesis of aminomethylated azaindole derivatives via domino copper-catalyzed multicomponent coupling and cyclization have been developed. Using various secondary amines and aldehydes, N-substituted 3-ethynyl-4-aminopyridine was converted to substituted azaindoles in moderate to excellent yields. By use of a 3,4-diaminopyridine derivative bearing two alkynyl groups, the corresponding pyrrole-fused azaindoles were synthesized by controlled stepwise cyclization.     

Synthesis of N-substituted indole derivatives via PIFA-mediated intramolecular cyclization

[Structure: see text] A variety of N-arylated and N-alkylated indole derivatives were synthesized by way of a phenyliodine bis(trifluoroacetate) (PIFA)-mediated intramolecular cyclization. This novel method allows for the construction of an indole skeleton by joining the N-atom on the side chain to the benzene ring at the last synthetic step. Other novel pyrrole-fused aromatic compounds can also be achieved by this method.     

A Synthesis of Two Novel Benzo[f]ninhydrin Analogs: 6-Methoxybenzo[f]ninhydrin and Thieno[f]ninhydrin

Improved methodology for the synthesis of benzo[f]ninhydrin (1) is described. The generality of this approach is illustrated with the synthesis of two novel analogs, 6-methoxybenzo[f]ninhydrin (3) and thieno[f]ninhydrin (4).     

The development of novel ninhydrin analogues

Following its discovery by Siegfried Ruhemann in 1910, ninhydrin rapidly became a practical analytical tool. In 1954 it was found to be an important reagent to develop fingerprints on porous surfaces. Since its use in forensic chemistry, many efforts have focused on improving the reagent. Many of the shortcomings of ninhydrin have been met by the synthesis of a variety of ninhydrin analogues. This tutorial review provides a short introduction to ninhydrin and highlights the different synthetic approaches used in the development of analogues for the detection of latent fingerprints.     

Progress in the Chemistry of Amino-Acid Derivatives of Isocoumarins and 3,4-Dihydroisocoumarins

Chemistry of Natural Compounds - Approaches to the synthesis of isocoumarins and 3,4-dihydroisocoumarins containing natural or synthetic amino-acid fragments are reviewed. Most attention is paid to...