Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions.

Iron- and cobalt-catalyzed Sonogashira coupling reactions are becoming central areas of research in organic synthesis. Owing to their significant importance in the formation of carbon-carbon bonds, numerous green and nanoparticle protocols have emerged during the past decades. The non-toxic and inexpensive nature of catalysts gained much attention in recent times. In this context, their catalytic nature and activity in Sonogashira coupling reactions were well explored and compared. Most importantly, one of the highlights of this review is the emphasis given to green strategies. This is the first review on iron- and cobalt-catalyzed Sonogashira coupling reactions which comprehends literature up to 2020.

Lead-halides Perovskite Visible Light Photoredox Catalysts for Organic Synthesis.

Lead-halide perovskites has grabbed great attention in recent years due to its unique photophysical and electrical properties. It has open new window in organic solar cell application for commercial point. Research has extended its application further towards visible light photoredox catalysts for organic synthesis. Due to intrinsic redox properties, sharp absorption and emissions patterns makes lead-halide perovskites as promising photoredox catalyst. In the presence of light, perovskite absorbs light, generates electrons/holes, which can reduce or oxidize species at reactive centres of organic molecule, leads to organic transformation. Lead-halide perovskites are used as heterogeneous catalysts for small molecules activations like CO, CH4 and NO, also suitable photocatalysts for organic bond formations, oxidations, reductions, polymerizations and dimerization transformations. Recent literatures have set another milestone for perovskite materials in organic synthesis. This review provides information on lead-halides perovskite in visible-light photoredox catalysis such as C-C, C-X (X-halo, hetero atom) bond formations C-H arylation.

Trash to Treasure: Eco-Friendly and Practical Synthesis of Amides by Nitriles Hydrolysis in WEPPA.

The hydration of nitriles to amides in a water extract of pomelo peel ash (WEPPA) was realized with moderate to excellent yields without using external transition metals, bases or organic solvents. This reaction features a broad substrate scope, wide functional group tolerance, prominent chemoselectivity, and good reusability. Notably, a magnification experiment in this bio-based solvent at 100 mmol further demonstrated its practicability.

Piperazine: An excellent catalyst for the synthesis of 2-amino-3-cyano-4H-pyrans derivatives in aqueous medium.

An improved, forthright, and highly efficient one-pot synthesis of a wide range of pharmaceutically exciting diverse kind of functionalized 2-amino-3-cyano-4H-pyrans and especially bis-pyrans compounds is developed using piperazine as a low-cost and environmentally benign commercially available basic catalyst in aqueous media. The attractive features of this process are simple procedure, short reaction times, high yields, no column chromatographic separation and commercial availability and recyclability of the catalyst. Also, piperazine can catalyze the synthesis of the target compounds on a larger scale. Furthermore, rational mechanism was suggested via GC-Mass analysis of the trapped intermediates.

"On-Water" Facile Synthesis of Novel Pyrazolo[3,4-b]pyridinones Possessing Anti-influenza Virus Activity.

A facile and versatile "on-water" protocol for the synthesis of pyrazolo[3,4-b]pyridinones was developed by the unprecedented construction of two rings and five new bonds in one-pot. It was proved that water was an important promoter of the reaction and PEG2000 was found to improve the reaction in terms of yield. 32 Derivatives were newly synthesized and most of them were prepared in an hour. The scope and limitation indicated that electron withdrawing groups substituted on synthons, substituted benzoyl acetonitriles or aryl aldehydes, were helpful to construct the pyrazolo[3,4-b]pyridinones. The reaction media PEG2000/H2O was successfully recycled and reused at least 5 times without any obvious decrease in yield. The anti-influenza activities of the derivatives were evaluated and the screening results highlighted two derivatives, which exhibited strong inhibitory activity against H5N1 pseudovirus. These positive bioassay results implied that the library of potential anti-influenza virus agent candidates could be rapidly prepared in an eco-friendly manner, and provided a new insight into drug discovery for medicinal chemists.