Double Cu-Catalyzed Direct Csp3 -H Azidation/CuAAC Reaction: A Direct Approach towards Demanding Triazole Conjugates.

The first one-pot procedure for the double copper(I)-catalyzed oxidative Csp3 -H azidation-CuAAC process, implying unstable azide intermediates and easy-to-remove reagents under water-tolerant conditions, is presented. The combination of tert-butyl hydroperoxide as oxidant and TMSN3 as azide source for the C-H bond azidation, which produces harmless side-products such as tBuOH and H2 O, probed to be perfectly compatible with the following cycloaddition step. Highly demanding 1,2,3-triazoles could be then directly obtained in good overall yields by extraction or simple crystallization, thus avoiding chromatography purifications. The potential of this methodology, has also being highlighted by the successful reaction of alkynes presenting interesting complex biological moieties based for example on biotin, DNA base or cinchona alkaloid units.

Direct C-H Bond Imidation with Benzoyl Peroxide as a Mild Oxidant and a Reagent.

A simple and mild Cu-catalyzed oxidative three-component oxidative Ugi-type method for the synthesis of a variety of substituted imides has been developed. In this direct imidation approach, benzoyl peroxide serves as both the oxidant and the carboxylate source, allowing not only the functionalization of C(sp3)-H bonds in α-position to an amine but also benzylic substrates. This procedure presents a wide substrate-type and functional group tolerance. Moreover, the mildness of the method permitted us to extend its application to the late stage functionalization of complex natural products such as the alkaloids brucine and strychnine, leading to interesting highly functionalized imide derivatives. On the basis of experimental and computational studies, a plausible mechanism has been proposed.

Recent progress in mild Csp3-H bond dehydrogenative or (mono-) oxidative functionalization.

Over the past few years, the development of oxidative methodologies towards efficient and selective direct Csp3-H bond functionalization processes has attracted tremendous attention from synthetic chemists. However, only a little attention has been given to the key role of the nature of the oxidant. This review aims at providing a brief summary of the recent advances in mild and more benign oxidative Csp3-H bond functionalization reactions, which are classified according to the type of oxidation system employed.

Direct Access to Unnatural Cyclobutane α-Amino Acids through Visible Light Catalyzed [2+2]-Cycloaddition.

In this work, we report the first selective, photocatalyzed [2+2]-cycloaddition of dehydroamino acids with styrene-type olefins. This simple, mild, and scalable approach relies on the use of the triplet energy transfer catalyst [Ir(dFCF3ppy2)dtbpy]PF6 under visible light irradiation and provides fast access to value-added substituted strained cyclobutane α-amino acid derivatives.

Easy access to drug building-blocks through benzylic C-H functionalization of phenolic ethers by photoredox catalysis.

A visible light-mediated photocatalyzed C-C-bond forming method for the benzylic C-H functionalization of phenolether containing synthetic building blocks based on a radical-cation/deprotonation strategy is reported. This method allows the mild, selective generation of benzyl radicals in phenolic complex molecules and drug-like compounds, providing new entries in synthetic and medicinal chemistry.