An efficient one-pot organocatalytic synthesis of 9-(1H-indol-3-yl)-xanthen-4-(9H)-ones under mild aqueous micellar conditions

Application of cyclohexane-1,3-diones for six-membered oxygen-containing heterocycles synthesis

Cyclohexan-1,3-dione derivatives are versatile scaffolds for the synthesis of a variety of value-added organic molecules including heterocycles and natural products. Six-membered oxygen heterocycles prepared from cyclohexan-1,3-diones are of much importance as they are intermediate for the synthesis of a number of natural products and several other valuable bioactive molecules which shows anti-viral, anti-bacterial, analgesic, antimalarial, anti-inflammatory, anti-allergic, anti-tumor and anti-cancer activities. These advantages have inspired us to write a detailed survey on the newly developed methods which are very essential in the construction of six-membered oxygen heterocycles. Further, the versatility in the chemistry of cyclohexan-1,3-dione and its derivatives is due to the presence of highly active methylene moiety and its active di-carbonyl groups. Recently, reactions of cyclohexane-1,3-dione and its derivatives with other substrates for instance aldehydes, malononitriles, NMSM, chalcones, isatin etc. have been established for the construction of a variety of six-membered oxygen heterocycles. The studies reported in this review article involved the synthesis of six-membered oxygen-containing heterocycles which includes 4H-chromen-5(6H)-one, 2H-xanthen-1(9H)-one, 2H-xanthen-1,8(5H,9H)-dione, 6H-chromen-2,5-dione derivatives and natural products having six-membered oxygen heterocycles from cyclohexane-1,3-dione and its derivatives as one of the substrate.

Norbornene Probes for the Detection of Cysteine Sulfenic Acid in Cells

Norbornene derivatives were validated as probes for cysteine sulfenic acid on proteins and in live cells. Trapping sulfenic acids with norbornene probes is highly selective and revealed a different reactivity profile than the traditional dimedone reagent. The norbornene probe also revealed a superior chemoselectivity when compared to a commonly used dimedone probe. Together, these results advance the study of cysteine oxidation in biological systems.

Recent advances in the application of indoles in multicomponent reactions

Indoles are some of the most versatile and common nitrogen-based heterocyclic scaffolds and are frequently used in the synthesis of various organic compounds. Indole based compounds are very important among heterocyclic structures due to their biological and pharmaceutical activities. The last decade, in particular, has witnessed considerable activity towards the synthesis of indole derivatives due to the possibilities for the design of polycyclic structures by the incorporation of multiple fused heterocyclic scaffolds in an attempt to achieve promising new heterocycles with chemical and biomedical relevance. In this study, we provide an overview on recent applications of indole in the multicomponent reactions for the synthesis of various heterocyclic compounds during the period of 2012 to 2017.

One-pot three-component protocol for the synthesis of indolyl-4H-chromene-3-carboxamides as antioxidant and antibacterial agents

A series of newly synthesized 4-(1H-indol-3-yl)-2-methyl-N-phenyl-4H-chromene-3-carboxamide derivatives catalyzed by 1,4-Diazabicyclo [2.2.2]octane (DABCO) (30 mol%) at room temperature.

Facile construction of 3-indolochromenes and 3-indoloxanthenes via EDDF catalyzed one-pot three component reactions

EDDF–ethylene glycol, an ambiphilic catalytic system has been employed for the mild and rapid synthesis of various 3-indolochromenes and 3-indoloxanthenesviaa one-pot MCR. Besides recyclability of the catalyst, the present method circumvents the formation of any by-products.

Efficient and regioselective synthesis of novel functionalized dispiropyrrolidines and their cytotoxic activities

An efficient and regioselective synthesis of novel functionalized dispiropyrrolizidine derivatives via a three-component [3 + 2] cycloaddition reaction of azomethine ylides is described. This protocol has the advantages of high efficiency, mild reaction conditions, a one-pot procedure, and convenient operation. Many of these compounds were evaluated for their antiproliferative properties in vitro against cancer cells and several compounds were found to have good activities.

Ligand-free copper-catalyzed efficient one-pot access of benzo[b]pyrido[3,2-f][1,4]oxazepinones through O-heteroarylation-Smiles rearrangement-cyclization cascade

An optimized protocol towards synthesis of benzopyrido[1,4]oxazepinones of potential biological relevance is achieved by coupling of N-substituted-o-chloronicotinamides and o-halogenated naphthols/phenols.

An organocatalyst from renewable materials for the synthesis of coumarins and chromenes: three-component reaction and multigram scale synthesis

A new concept of catalysts which are prepared from renewable materials is demonstrated for the synthesis of coumarins and chromenes.

An efficient regioselective bromination protocol of activated coumarins using 2,4,4,6-tetrabromo-2,5-cyclohexadienone

2,4,4,6-Tetrabromo-2,5-cyclohexadienone mediated bromination of a wide assortment of activated coumarins in acetonitrile has been accomplished with high regioselectivity and good to excellent yields. The selectivity and efficiency of bromination were found to be markedly dependent on electronic factors, particularly degree of electron withdrawal from electron-releasing 7-oxygenated substituents to the C-3 position of the α-pyrone moiety by vinylogous resonance and the presence of nucleophilic additives such as water and tetra-n-butylammonium bromide in the reaction medium. The sole by-product of the reaction was converted back to the reagent by oxidation with KBr−KBrO3, which was recycled three times without significant loss of efficiency.

Efficient synthesis of functionalized dihydro-1H-indol-4(5H)-ones via one-pot three-component reaction under catalyst-free conditions

A facile and efficient one-pot procedure for the preparation of functionalized dihydro-1H-indol-4(5H)-ones by a catalyst-free, three-component reaction of 1,3-dicarbonyl compounds, arylglyoxal monohydrate and enaminones under mild conditions in excellent yield is reported. This synthesis was confirmed to follow the group-assisted-purification (GAP) chemistry process, which can avoid traditional purifications, chromatography, and recrystallization.