The in situ observation, isolation and reversible formation of intermediate 3-(hydroxybenzyl)azolium salts derived from NHC addition to a range of substituted benzaldehydes is probed. Equilibrium constants for the formation of these 3-(hydroxybenzyl)azolium salts, as well as rate constants of hydrogen-deuterium exchange (k ex) at C(a) of these intermediates for a range of N-aryl triazolinylidenes is reported. These combined studies give insight into the preference of N-pentafluorophenyl NHCs to participate in benzoin and Stetter reaction processes.

Rate and equilibrium constants for the reaction between N-aryl triazolium N-heterocyclic carbene (NHC) precatalysts and substituted benzaldehyde derivatives to form 3-(hydroxybenzyl)azolium adducts under both catalytic and stoichiometric conditions have been measured. Kinetic analysis and reaction profile fitting of both the forward and reverse reactions, plus onwards reaction to the Breslow intermediate, demonstrate the remarkable effect of the benzaldehyde 2-substituent in these reactions and provide insight into the chemoselectivity of cross-benzoin reactions.

The incorporation of orthophosphate from scarce geochemical sources into the organic compounds essential for life under mild conditions is a fundamental challenge for prebiotic chemistry. Here we report a prebiotic system capable of overcoming this challenge by taking inspiration from extant life’s recycling of orthophosphate via its conversion into kinetically stable thermodynamically activated (KSTA) nucleotide triphosphates (e.g. ATP). We separate the activation of orthophosphate from its transfer to organic compounds by, crucially, first accumulating a KSTA phosphoramidate. We use cyanate to activate orthophosphate in aqueous solution under mild conditions and then react it with imidazole to accumulate the KSTA imidazole phosphate. In a paste, imidazole phosphate phosphorylates all the essential building blocks of life. Integration of this chemistry into a wet/dry cycle enables the continuous recycling of orthophosphate and the accretion of phosphorylated compounds. This system functions even at low reagent concentrations due to solutes concentrating during evaporation. Our system demonstrates a general strategy for how to maximise the usage of scarce resources based upon cycles which accumulate and then release activated intermediates.

Many natural and man-made complex systems display early warning signals when close to an abrupt shift in behaviour. Here we show that such early warning signals appear in a complex chemical reaction network.

Currente fforts to design functional molecular systems have overlooked the importance of coupling out-ofequilibrium behaviour with changes in the environment. Here, the authors use an oscillating reaction network and demonstrate that the application of environmental forcing, in the form of periodic changes in temperature and in the inflow of the concentrationo fo ne of the network components, removes the dependency of the periodicity of this network on temperature or flow rates and enforces as table periodicity across aw ide range of conditions. Coupling a system to ad ynamic environmentc an thusb eu sed as a simple tool to regulate the output of an etwork. In addition, the authors show that coupling can also induce an increase in behavioural complexity to include quasi-periodic oscillations. Institute for Molecules and Materials, RadboudU niversity Heyendaalseweg 135, 6525 AJ Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.