Supramolecular Control of a Fast and Reversible Diels−Alder Reaction

Abstract

A new cyclophane featuring two opposite anthracene units linked in 9,10-positions has been synthesized thanks to the template effect of the Me4N(+) ion. It forms pseudorotaxane complexes with alkylviologen ions and undergoes a fast and reversible reaction with tetracyanoethylene. A quantitative analysis has been carried out of the formation of Diels-Alder adducts, whose distribution can be controlled by host-guest complexation. These findings open interesting perspectives in the field of Dynamic Covalent Chemistry.

Dynamic Diels–Alder Reactions of 9,10‐Dimethylanthracene: Reversible Adduct Formation, Dynamic Exchange Processes and Thermal Fluorescence Modulation

“…Spiro [2,4]hepta-4,6-diene (5), [19] 9,10-dimethoxylanthracene (8), [20] 4-phenylbut-1-en-3-yne-1,1,2-tricarbonitrile (11), [12b] 2-cyano-3-{[4-(dimethylamino)phenyl]ethynyl}but-2-enedinitrile (12), [13] (E)-4-[4-(dimethylamino)phenyl]buta-1,3-diene-1,1,2-tricarbonitrile (13) [14] and 2-[4-(dimethylamino)phenyl]-1,1,2-tricyanoethylene (14) [14,21] were synthesized according to the procedure described in the literature. The following procedures were adapted from the literature.…”

“…[7] Supramolecular control of reversible DA reactions on anthracene units contained in a cyclophane has been reported recently. [8] Among the dienophiles that have been used, fullerene plays a particular role owing to its nature and to the low temperature at which its retro-reaction takes place. 9,10-Dimethylanthracene reacts with fullerene at room temperature up to six times, and the adducts formed dissociated reversibly at this temperature.…”

Polymer mechanochemistry: the design and study of mechanophores

“…As Diels–Alder adducts (e.g. oxanorbornene derivatives) have been implemented in dynamic covalent materials, mechanically facilitated [4 + 2] cycloreversions are particularly relevant for the development of various stimulus‐responsive systems . To determine the viability of mechanically induced retro‐[4 + 2] reactions, PMA was grown from an oxanorbornene‐based bifunctional polymerization initiator and then subjected to ultrasonication.…”

Selected synthetic strategies to cyclophanes

“…The aromatic rings provide rigidity to their structure, whereas the aliphatic unit(s) form bridge(s) between the aromatic rings and also provide flexibility to the overall structure. Cyclophanes play an important role in “host–guest” chemistry [ 39 – 43 ] and supramolecular assembly [ 44 – 47 ]. “Phane”-containing molecules show interactions with π-systems, and they can also bind to a large number of cations, anions, and neutral molecules.…”