Synthesis of Tetra-ortho-Methoxylated Azobenzene Photoswitches via Sequential Catalytic C-H Activation and Methoxylation

Functionalized tetra-ortho-methoxyazobenzenes have been prepared in a two-step approach based on palladium-catalyzed C-H ortho bromination of azobenzenes, followed by copper-catalyzed methoxylation. The method has shown a broad tolerance to different functional groups that could not be incorporated by previous strategies. With this two-step transition metal-catalyzed strategy, we achieved overall yields that range from good to excellent and enable the exploitation of these highly coveted photoswitches. The superior robustness of this scaffold for solid phase peptide synthesis (SPPS) applications when compared to its chlorinated counterpart has been demonstrated after extensive treatments with piperidine while bound to a RinkAmide ChemMatrix resin, showcasing their potential for use in the synthesis of red-light-operated peptides.

Transition-Metal-Catalyzed Directed C-H Functionalization in/on Water

Directing group assisted C-H bond functionalization using transition-metal-catalysis has emerged as a reliable synthetic tool for the construction of regioselective carbon-carbon/heteroatom bonds. Off late, "in/on water directed transition-metal-catalysis", though still underdeveloped, has appeared as one of the prominent themes in sustainable organic chemistry. This article covers the advancements, mechanistic insights and application of the sustainable directed C-H bond functionalization of (hetero)arenes in/on water in the presence of transition-metal-catalysis.

Revisiting the mechanism of the Fujiwara–Moritani reaction

A new perspective of the Fujiwara–Moritani reaction is presented, including its kinetic profile and catalyst deactivation studies.

Multiple pathways for C–H cleavage in cationic Cp*Rh(iii)-catalyzed C–H activation without carboxylate assistance: a computational study

Multiple pathways for C–H cleavage was uncovered in cationic Cp*Rh(iii)-catalyzed C–H functionalization with different heteroatom-containing species as possible proton acceptors.

Unveiling the mechanisms and secrets of chemoselectivities in Au(i)-catalyzed diazo-based couplings with aryl unsaturated aliphatic alcohols

The mechanisms and origins of the unsaturated-aliphatic-alcohols-modulated chemoselectivity of Au-catalyzed carbene transfers from diazo compounds are disclosed by DFT studies.

Mechanisms for C(sp2)-Si activation of aryltrimethylsilyl groups in palladium-catalysed couplings

Silyl-substituted aromatic compounds can participate as the electrophilic component in palladium-catalysed cross-couplings, and reactivity is enhanced by a neighbouring silyl-group. Products analogous to those obtained from C-H activation chemistry are accessible by this means with the additional benefit of regiochemistry defined by the site of silyl substitution. DFT studies described here show that the mechanism of C-Si cleavage is distinct from previously recognised mechanisms for C-H cleavage, with a cascade of silyl intermediates en route to a stable product. The amide directing-groups are involved only in the stabilisation of palladacyclic intermediates, and are never disposed to activate silicon directly. 5-Membered and 6-membered palladacycles are known to behave differently in coupling reactions and the calculations reveal underlying reasons in the cationic pathways studied here.

Computational Studies of Carboxylate-Assisted C-H Activation and Functionalization at Group 8-10 Transition Metal Centers

Computational studies on carboxylate-assisted C-H activation and functionalization at group 8-10 transition metal centers are reviewed. This Review is organized by metal and will cover work published from late 2009 until mid-2016. A brief overview of computational work prior to 2010 is also provided, and this outlines the understanding of carboxylate-assisted C-H activation in terms of the "ambiphilic metal-ligand assistance" (AMLA) and "concerted metalation deprotonation" (CMD) concepts. Computational studies are then surveyed in terms of the nature of the C-H bond being activated (C(sp²)-H or C(sp³)-H), the nature of the process involved (intramolecular with a directing group or intermolecular), and the context (stoichiometric C-H activation or within a variety of catalytic processes). This Review aims to emphasize the connection between computation and experiment and to highlight the contribution of computational chemistry to our understanding of catalytic C-H functionalization based on carboxylate-assisted C-H activation. Some opportunities where the interplay between computation and experiment may contribute further to the areas of catalytic C-H functionalization and applied computational chemistry are identified.