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Herein, we report an efficient metal-free system for the transfer hydrogenation of esters and carbonates with ammonia borane as hydrogen donor, by-passing the otherwise ubiquitous formation of transesterification side-products.

The utilization and valorization of agricultural waste is a key strategy for the implementation of a sustainable economy to lessen the environmental footprint of human activities on Earth. This work describes the use of rice husk (RH) from agricultural waste to prepare a highly active catalyst for the reduction of nitro compounds. RH was impregnated with various cobalt complexes bearing N-donor ligands, then pyrolyzed and the resulting composite was etched with a base to remove the silica domains. The composition and morphology of the prepared materials were investigated by IR, AAS, ICP-OES, XRD, BET, XPS and SEM technics. The material showed excellent activity and selectivity in the hydrogenation of nitro groups in aromatic and aliphatic substrates. A remarkable selectivity towards nitro groups was found in the presence of various reactive functionalities, including halogens, carbonyls, borates, and nitriles. Apart from their excellent activity and selectivity, these catalysts showed remarkable stability, allowing their easy recovery and multiple reuse without requiring re-activation.

Catalytic allylation reactions are important methodologies to introduce the versatile allyl functionality into molecules to produce fine chemicals and synthetic building blocks. Since the first reports by Tsuji and Trost, many improvements on allylation technologies have been reported. The introduction of photocatalytic techniques marked one of the major breakthroughs in this field, complementing the existing thermal chemo-catalyzed protocols, providing high selectivity under milder conditions. This review discloses state-of-the-art photocatalyzed allylation methodologies, their reaction mechanisms, and synthetic applications. The reactions are classified according to the employed catalysts, namely single photocatalyst and dual-catalytic approaches. Finally, each methodology is individually presented and evaluated based on the performance of the reaction.

Silicones and silicone rubbers are ubiquitous in our daily lives, being used in a broad range of applications ranging from consumer products and adhesives to medicinal and electronic devices. The chemistry and synthesis of these versatile materials have been reviewed so many times that it is difficult to have a comprehensive overview. Hence, with this tutorial review we aim to provide a concise account of the most important reactions and industrial processes to furnish silicones, focusing specially on reactive silicones, specifically in telechelic OH-terminated polysiloxanes, which represent one of the most relevant members of this important materials family.

C.Li thanks the Prof. & Mrs Purdie Bequests Scholarship and AstraZeneca PhD Studentship. A family of six structurally related heteroleptic copper(I) complexes of the form of [Cu(N^N)(P^P)]+ bearing a 2,9-dimethyl-1,10-phenanthroline diimine (N^N) ligand and a series of electronically tunable xantphos (P^P) ligands have been synthesized and their optoelectronic properties characterized. The reactivity of these complexes in the copper-photocatalyzed Aza-Henry reaction of N-Phenyltetrahydroisoquinoline was evaluated, while the related excited state kinetics were comprehensively studied. By subtlety changing the electron-donating properties of the P^P ligands with neglegible structural differences, we could tailor the photoredox properties and relate it to their reactivity. Moreover, depending on the exited-state redox potential of the catalysts, the preferred mechanism can shift between reductive quenching, energy transfer and oxidative quenching pathways. A combined study of structural modulation of copper(I) photocatalysts, optoelectronic properties and photocatalytic reactivity resulted in a clearer understanding of both the rational design of the photocatalyst and the complexity of competing photoinduced electron and energy transfer mechanisms. Publisher PDF