Tetrahedron Green Chem最新文献

A metal-free, efficient, and eco-friendly on-water protocol for the synthesis of quinazolinone derivatives via a tandem one-pot three-component reaction using a novel, efficient, and recyclable heterogeneous catalyst, [CA@MIP] – melamine-based covalent organic polymer supported citric acid, has been described. The catalyst has been synthesized by a simple procedure and is well characterized by numerous spectroscopic techniques such as Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM), Powder X-ray diffraction (PXRD), Brunauer-Emmett-Teller (BET), Energy Dispersive X-ray (EDX), and Thermal Gravimetric (TG) analyses. [CA@MIP] showed excellent catalytic potential offering quinazolinones in excellent yields (>85%) in a short reaction time period and was reusable for up to five successive runs.

The use of biobased polymers or natural inorganic materials in place of synthetic polymers or liquid crystals derived from petroleum to fabricate optical components establishes the concept of “sustainable optics”, at least for what concerns the environmental dimension of sustainability as these polymers are renewable and often biodegradable or compostable. To identify the main obstacles to be addressed prior to industrial uptake of these polymeric resins in the optics industry, we focus on two promising and widely studied biobased polymeric materials, namely nanocellulose and poly(limonene carbonate). The conclusions have implications also for the emerging bioeconomy and the undergoing reshaping of the chemical industry driven by sustainability megatrend.

The food industry generates vast amounts of waste and one of the most abundant is the biopolymer chitin, which is the main constituent of crustacean shells and insect exoskeletons. The alkaline deacetylation of the N-acetyl-d-glucosamino units of chitin leads to chitosan, a stable, inexpensive, non-toxic, biocompatible, and biodegradable material of basic properties due to the presence of free amino groups. In the present study, we report the catalytic activity of commercially available chitosan as a sustainable heterogeneous catalyst for the preparation of α-diazo carbonyl compounds through the diazo transfer reaction to active methylene compounds using a sulfonyl azide as the diazo transfer reagent. Thus, 17 α-diazo carbonyl compounds were readily prepared under mild conditions in 50–92% yield after a simple work-up consisting of vacuum filtration to separate the insoluble catalyst and the sulfonamide byproduct. This procedure was also adapted to aqueous medium, making the process more environmentally benign. The recovery and recyclability of the biocatalyst were also addressed, with the catalytic activity being slightly reduced after four reuses depending on the substrate used. The synthetic potential of diazo carbonyl compounds was further demonstrated through the rhodium-catalyzed O–H insertion reactions.

The electrochemical oxidation of sec-alcohols has been achieved using MgBr₂·6H₂O as an inexpensive active bromine source and electrolyte under constant current conditions. The reactions smoothly proceed in a simple undivided cell, and aliphatic/benzylic sec-alcohols bearing heteroaromatics as well as aryl and alkyl groups are successfully converted to the corresponding ketones in good to excellent yields. In addition, the present reaction conditions selectively transform a secondary hydroxy moiety over different classes of hydroxy groups.