Related Experiment Video
Updated: Jul 15, 2026

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)
Published on: June 20, 2014
Temporal dependence emerges from a carbodiimide driven acid-anhydride equilibrium coupled to a photocatalytic
Rens Ham1, Bettina Baumgartner1, Joost N H Reek1
1Van 't Hoff Institute for Molecular Sciences, University of Amsterdam 1098 XH Amsterdam The Netherlands j.n.h.reek@uva.nl.
Abstract:
Neurons process multiple stimuli in a temporally dependent manner, which filters noise and enables precise control over complex functions. Synthetically mimicking neuronal processes may be useful for autonomous chemical systems that are able to make their own decisions, yet such time-dependence has not found an equivalent in synthetic reaction networks. Herein, we show that carbodiimide driven equilibria between acid and anhydride can be coupled to photochemical decarboxylation from which temporal input dependence emerges. Under optimized conditions, the decarboxylation of the anhydride is much faster than the acid. However, the anhydride hydrolyses back to the acid, and as such is only temporally present after carbodiimide addition, which limits its conversion to this time period. The network therefore displays temporal dependence, as the product is only generated when both carbodiimide and light inputs align in time. Such systems provide a platform to explore the role of temporal gating in biological regulation and offer new strategies for adaptive catalysis and chemical computing.
Related Concept Videos
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Thermal and Photochemical Electrocyclic Reactions: Overview
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
