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Gold carbene reactivity patterns were accessed by ynamide insertion into a C(sp3)-H bond. A substantial increase in molecular complexity occurred through the cascade polycyclization of N-allyl ynamides to form fused nitrogen-heterocycle scaffolds. Exquisite selectivity was observed despite several competing pathways in an efficient gold-catalyzed synthesis of densely functionalized C(sp3)-rich polycycles and a copper-catalyzed synthesis of fused pyridine derivatives. The respective gold–keteniminium and ketenimine activation pathways have been explored through a structure–reactivity study, and isotopic labeling identified turnover-limiting C-H bond-cleavage in both processes. [ABSTRACT FROM AUTHOR]

The rapidly expanding field of gold and platinum π-acid catalysis has led to the discovery of diverse transformations that are initiated with nucleophilic attack onto a metal-activated alkyne. This review brings together those reactions which employ a heteroatom nucleophile bearing a functional group that can subsequently migrate to effect a formal insertion of the alkyne into a carbon- heteroatom σ-bond. This reactivity profile is encountered in a range of efficient and powerful cycloisomerisations for the preparation of carbo- and heterocycles. 1 Introduction 2 1,2-Addition of Carbon-Heteroatom Bonds across Alkynes 2.1 Heteroatom-to-Carbon Allyl Migrations 2.2 Accessing Sigmatropic Rearrangements 2.3 Related Palladium-Catalysed 1,2-Carboalkoxylations and Carboaminations 2.4 Beyond Allyl Migration in the 1,2-Carbofunctionalisation of Alkynes 2.5 Oxonium Ion Migration 2.6 Migrating Centres at Higher Oxidation Levels 2.7 Migration of Heteroatoms 3 1,5 Heteroatom-to-Carbon Migrations 3.1 Alkynyl Benzoates as Alkylating Agents 4 Internal versus External Migrations 4.1 Internal Migrations of Oxonium Species 5 1,1-Carbofunctionalisations 6 Application in Natural Products 7 Summary and Conclusions [ABSTRACT FROM AUTHOR]

The conceptual replacement of nitrogen with phosphorus in common organic functional groups unlocks new properties and reactivity. The phosphorus-containing analogues of triazenes are underexplored but offer great potential as flexible and small bite-angle ligands. This manuscript explores the synthesis and characterisation of a family of air-stable azophosphine-borane complexes, and their subsequent deprotection to the free azophosphines. These compounds are structurally characterised, both experimentally and computationally, and highlight the availability of the phosphorus lone pair for coordination. This is confirmed by demonstrating that neutral azophosphines can act as ligands in Ru complexes, and can coordinate as monodentate or bidentate ligands in a controlled manner, in contrast to their nitrogen analogues., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

A series of highly substituted tetrahydrofurans (THFs), decorated with modifiable 2-aryl, 3-carboxy and 4-amino substituents, has been prepared for biological evaluation within the European Lead Factory. Diastereoselective reductive amination of pre-functionalised 4-oxofurans, readily prepared from cinnamate esters via oxa-Michael/Dieckmann annulation, provided the requisite THF cores on gram scale with three contiguous stereocentres, including full substitution at C-3. In a second series, a pyrrolidine ring was fused to the same oxofuran scaffold via an intramolecular reductive amination, inverting the configuration at C-4 relative to the other ring substituents. The resulting compounds, which displayed desirable physical properties as lead-like scaffolds, were derivatised into a small library of 24 compounds, demonstrating their ability to serve as starting points for drug discovery. Ultimately, this chemistry enabled the preparation of 1948 THF-containing compounds for inclusion in the Joint European Compound Library., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Unique α-hemiaminal ether gold carbene intermediates were accessed by a gold-catalysed 1,1-carboalkoxylation strategy and evolved through a highly selective 1,2-N-migration. This skeletal rearrangement gave functionalised indenes, and isotopic labelling confirmed the rare C-N bond cleavage of the ynamide moiety. The effect of substituents on the migration has been explored, and a model is proposed to rationalise the observed selectivity., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)