[3+3] Cyclocondensation of Disubstituted Biphenyl Dialdehydes: Access to Inherently Luminescent and Optically Active Hexa-substituted C₃-Symmetric and Asymmetric Trianglimine Macrocycles

Abstract

A general synthetic route to inherently luminescent and optically active 6-fold substituted C-symmetric and asymmetric biphenyl-based trianglimines has been developed. The synthesis of these hexa-substituted triangular macrocycles takes advantage of a convenient method for the synthesis of symmetrically and asymmetrically difunctionalized biphenyl dialdehydes through a convergent two-step aromatic nucleophilic substitution-one-pot Suzuki-coupling reaction protocol. A modular [3+3] diamine-dialdehyde cyclocondensation reaction between both the symmetrically and asymmetrically difunctionalized-4,4'-biphenyldialdehydes with enantiomerically pure (1R,2R)-1,2-diaminocyclohexane was employed to construct the hexa-substituted triangular macrocycles. B97-D/6-311G(2d,p) density functional theory determined structures and X-ray crystallographic analysis reveal that the six substituents appended to the biphenyl legs of the trianglimine macrocycles adopt an alternating conformation not unlike the 1,3,5-alternate conformation observed for calix[6]arenes. Reduction of the imine bonds using NaBH afforded the corresponding 6-fold substituted trianglamine without the need to alkylate the amine nitrogen atoms which could hinder their later use as metal coordination sites and without having to introduce asymmetric carbons.

Electronic and vibrational exciton coupling in oxidized trianglimines

“…Highly symmetrical, large‐ring poly‐aza chiral macrocycles are of considerable interest because of their applications as molecular building blocks, catalysts, gelators, and discriminating agents . The synthetic method providing such compounds relies on thermodynamically driven cycloimination of dialdehydes with vicinal diamines of the trans ‐1,2‐diaminocyclohexane or threo ‐1,2‐diphenyl‐1,2‐diaminoethane type .…”

Sterically Crowded Trianglimines—Synthesis, Structure, Solid‐State Self‐Assembly, and Unexpected Chiroptical Properties

“…[12] Another advantage of trianglimines over other types of such macrocycles relies on easy control of the macrocycle cavity.T he use of biphenyl, terphenyl, or polyene linker significantly increasedt he macrocycle cavity,u sually at the expense of solubility. [14] To date, there are only af ew examples of trianglimines with one or two smalla nd/or polar groups in each of the aromatic rings. [14b, 15, 16] In spite of the strong effect of these substituents on the properties of the given macrocycle,i ti sh ard to consider thesec ases as trianglimines grown up-and/ord ownwards.…”

Recent Advances in the Synthesis and Applications of Nitrogen-Containing Macrocycles

“…Gelation properties of some trianglimines [ 23 , 24 ] was also studied using their urea and tiourea derivatives [ 25 ]. The series of macrocycles presented in the work also differed in aromatic fragments ( Figure 8 ).…”