Discerning Torquoselectivity of Non-Competitive and Competitive Ring-Opening Reactions Using QTAIM and Stress Tensor

Within this study, four thermal ring-opening reactions, Reactions (1-4), were selected in order to investigate the phenomenon of torquoselectivity as well as predicting non-competitive or competitive reactions in QTAIM and stress tensor frameworks rather than using conventional methods. The theoretical analysis for these reactions exhibits differently for non-competitive and competitive reactions as well as for the conrotatory preferences either TSOC or TSIC directions by presenting degeneracy or non-degeneracy in their results. The concordant results of stress tensor and QTAIM scalar and vectors with experimental results provide a better understanding of all reactions mechanism. Examination the (rb), ε, H(rb), ℙσ, 3, BPL, and H indicate that Reaction 1 is a competitive and Reactions (2-4) are non-competitive reactions with TSOC, TSOC, and TSIC preference directions respectively.

Direct Transamidation Reactions: Mechanism and Recent Advances

Amides are undeniably some of the most important compounds in Nature and the chemical industry, being present in biomolecules, materials, pharmaceuticals and many other substances. Unfortunately, the traditional synthesis of amides suffers from some important drawbacks, principally the use of stoichiometric activators or the need to use highly reactive carboxylic acid derivatives. In recent years, the transamidation reaction has emerged as a valuable alternative to prepare amides. The reactivity of amides makes their direct reaction with nitrogen nucleophiles difficult; thus, the direct transamidation reaction needs a catalyst in order to activate the amide moiety and to promote the completion of the reaction because equilibrium is established. In this review, we present research on direct transamidation reactions ranging from studies of the mechanism to the recent developments of more applicable and versatile methodologies, emphasizing those reactions involving activation with metal catalysts.