Enroute sustainability: metal free C-H bond functionalisation.

The term "C-H functionalisation" incorporates C-H activation followed by its transformation. In a single line, this can be defined as the conversion of carbon-hydrogen bonds into carbon-carbon or carbon-heteroatom bonds. The catalytic functionalisation of C-H bonds using transition metals has emerged as an atom-economical technique to engender new bonds without activated precursors which can be considered as a major drawback while attempting large-scale synthesis.

Transition metal catalyzed C-H bond activation by -metallacycle intermediates.

-Metallacycles have become the key reaction intermediates in activating various remote C(sp)-H and C(sp)-H bonds in the past decade and aided in achieving unusual site-selectivity. Various novel -chelating auxiliaries have assisted metals to reach desired remote C-H bonds of different alcohol and amine-derived substrates. As a result, a wide range of organic transformations of C-H bonds like halogenation, acetoxylation, amidation, sulfonylation, olefination, acylation, arylation, were accessible using the -metallacycle strategy.

Transition metal-free catalytic reduction of primary amides using an abnormal NHC based potassium complex: integrating nucleophilicity with Lewis acidic activation.

An abnormal N-heterocyclic carbene (aNHC) based potassium complex was used as a transition metal-free catalyst for reduction of primary amides to corresponding primary amines under ambient conditions. Only 2 mol% loading of the catalyst exhibits a broad substrate scope including aromatic, aliphatic and heterocyclic primary amides with excellent functional group tolerance. This method was applicable for reduction of chiral amides and utilized for the synthesis of pharmaceutically valuable precursors on a gram scale.

Storing redox equivalent in the phenalenyl backbone towards catalytic multi-electron reduction.

Storing and transferring electrons for multi-electron reduction processes are considered to be the key steps in various important chemical and biological transformations. In this work, we accomplished multi-electron reduction of a carboxylic acid a hydrosilylation pathway where a redox-active phenalenyl backbone in Co(PLY-O,O)(THF), stores electrons and plays a preponderant role in the entire process. This reduction proceeds by single electron transfer (SET) from the mono-reduced ligand backbone leading to the cleavage of the Si-H bond.