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The regiodivergent synthesis of 4‐ and 5‐sulfenyl oxazoles from 1,4,2‐dioxazoles and alkynyl thioethers has been achieved. Gold‐catalysed conditions are used to favour the formation of 5‐sulfenyl oxazoles via β‐selective attack of the nitrenoid relative to the sulfenyl group. In contrast, 4‐sulfenyl oxazoles are formed by α‐selective reaction under Brønsted acid conditions from the same substrates. The nature of stabilising gold‐sulfur interactions have been investigated by natural bond orbital analysis, showing that the S→Au interactions are significantly stronger in the intermediate that favours the 5‐sulfenyl oxazoles. A kinetic survey identifies catalyst inhibition processes. This study into the regiodivergent methods includes the development of telescoped annulation‐oxidation protocols for regioselective access to oxazole sulfoxides and sulfones. [ABSTRACT FROM AUTHOR]

In Nature, enzymatic reactions proceed through exceptionally ordered transition states giving rise to extraordinary levels of stereoselection. In those reactions, the active site of the enzyme plays crucial roles – through one position, it holds the substrate in the proximity to the reaction epicentre that facilitates both the reactivity and stereoselectivity of the chemical process. Inspired by this natural phenomenon, synthetic chemists have designed bifunctional ligands that not only coordinate to a metal centre but also preassociate with an organic substrate, for example aldehyde and ketone, and exerts stereodirecting influence to accelerate the attack of the incoming reacting partner from a particular enantiotopic face. The chief goal of the current review is to give an overview of the recently developed approaches enabled by privileged bio‐inspired bifunctional ligands that not only bind to the metal catalyst but also activates carbonyl substrates via organocatalysis, thereby easing in the new bond forming step. As carbonyl α‐functionalizations are dominated by enamine and enolate chemistry, the current review primarily focusses on enamine‐ and enolate‐metal catalysis by bifunctional ligands. Thus, developments based on traditional cooperative catalysis occurring through two directly coupled but independent catalytic cycles of an organocatalyst and a metal catalyst are not covered. [ABSTRACT FROM AUTHOR]

A methodical mechanistic investigation allowed for the catalytic N-acylation of secondary cyclic amine counterparts by arylglyoxylic acids through radical-radical coupling. The reaction proceeds via a twofold SET-promoted Cu(I)/Cu(II) catalytic cycle under mild conditions. An analogous reaction variant allows for the N-acylation in a one-pot fashion directly starting from a secondary cyclic amine even in the presence of a second amine or hydroxy group. [ABSTRACT FROM AUTHOR]