Enforced Electronic-Donor-Acceptor Complex Formation in Water for Photochemical Cross-Coupling

The amino alcohol meglumine solubilizes organic compounds in water and enforces the formation of electron donor acceptor (EDA) complexes of haloarenes with indoles, anilines, anisoles or thiols, which are not observed in organic solvents. UV-A photoinduced electron transfer within the EDA complexes induces the mesolytic cleavage of the halide ion and radical recombination of the arenes leading, after rearomatization and proton loss to C-C or C-S coupling products. Depending on the substitution pattern selective and unique cross-couplings are observed. UV and NMR measurements reveal the importance of the assembly for the photoinduced reaction. Enforced EDA aggregate formation in water allows new activation modes for organic photochemical synthesis.

Meglumine-Promoted Eco-Compatible Pseudo-Three-Component Reaction for the Synthesis of 1,1-Dihomoarylmethane Scaffolds and Their Green Credentials

A simple, straightforward, and energy-efficient greener route for the synthesis of a series of biologically interesting functionalized 1,1-dihomoarylmethane scaffolds has been developed in the presence of meglumine as an efficient and eco-friendly organo-catalyst via one-pot pseudo-three-component reaction at room temperature. Following this protocol, it is possible to synthesize 1,1-dihomoarylmethane scaffolds of an assortment of C-H activated acids such as dimedone, 1,3-cyclohexadione, 4-hydroxy-6-methyl-2-pyrone, 4-hydroxycoumarin, and 1-phenyl-3-methyl-pyrazolone. The salient features of the present green protocol are mild reaction conditions, good to excellent yields, operational simplicity, easy isolation of products, no cumbersome post treatment, high atom economy, and low E-factor. In addition, this chemistry portrays several green advantages including the reusability of reaction media and product scalability, which makes protocol sustainably efficient. Additionally, several control experiments such as protection of catalyst reactive site, D₂O exchange, and ¹H NMR studies revealed possible pathways for meglumine-promoted reactions. Inspired by the natural physiological environment of 1,1-dihomoarylmethane scaffolds, we reconnoitered the biological profile of our compounds and synthesized compounds that were promising for their antiproliferative and antibacterial activities.

Recent Progress in the Synthesis of Heterocycles Based on 1,3-Diketones

N,O-heterocycles containing the dicarbonyl ring play a significant role in heterocyclic and therapeutic chemistry. Since the discovery of 1,3-diketones, numerous research works have been achieved regarding the synthesis and its chemical reactivity. In this review, we have described the most relevant publications involving β-diketone compounds published during the period between 2018 to date. In addition, we include the 1,3-diketones-based heterocyclic compounds prepared by various synthetic methodologies.

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.