Redox equivalent storage in the phenalenyl backbone towards catalytic multi-electron reduction.

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.

cAAC)Fe(CO) 4 ] (1) catalyzed head-to-head dimerization of terminal arylalkynes toward conjugated enynes in very high yield and high E selectivity (up to 84:16 E:Z). The protocol can be performed under extremely low catalyst loading down to 0.01 mol %, resulting in a high TON of 6500. A mechanistic pathway for arylalkyne dimerization has been proposed on the basis of a well-defined catalyst, an isolable intermediate, and quantum chemical calculations.

The metal-free C–H functionalisation is providing environmentally benign, cost-effective, sustainable catalytic systems. Comprehensive developments of various metal-free C–H functionalisation reactions are the focal point of this review.

Allyl alcohols represent a unique class of coupling partners in C–H functionalization reactions. In this work, we report a simple strategy that involves dual-1,1-C­(sp3)–H activation of free aliphatic acids, leading to the direct synthesis of γ-lactones that contain α,β-unsaturated groups at the γ-position. Various allyl alcohols including primary, secondary, tertiary, etc., have been used as suitable coupling partners to generate a diverse range of γ-lactones. A number of aliphatic acids including the long-chain ones have been used as substrates in the protocol. A mechanistic investigation has been carried out and suggests C–H activation to be the rate-determining step and a subsequent allylic C–H activation in the reaction. The synthesized lactones having α,β-unsaturated fragments attached are expected to be useful in the synthesis of complex molecules via further synthetic manipulation.

Exo-metallacycles have become key reaction intermediates in activating various remote C(sp2)–H and C(sp3)–H bonds in the past decade and aided in achieving unusual site-selectivity. Various novel exo-chelating auxiliaries have assisted...