Compounds Based on a Triethyl- or Trimethoxybenzene Scaffold Bearing Pyrazole, Pyridine, and Pyrimidine Groups: Syntheses and Representative Binding Studies towards Carbohydrates

Abstract

Pyrazole-based artificial receptors have often been used in the recognition of ions, but in the area of sugar recognition the potential of pyrazole-based recognition groups has only been rarely examined. In this paper we describe the syntheses of twelve new pyrazolebearing compounds, which are all potentially applicable for use as carbohydrate receptors. The prepared compounds enforce tripodal architecture and are based on a triethyl-or trimethoxybenzene scaffold. Representative complexation studies with selected carbohydrates showed interesting binding preferences of the new compounds.

Compounds Derived from 9,9‐Dialkylfluorenes: Syntheses, Crystal Structures and Initial Binding Studies (Part II)

“…Biphenyl, [7a] diphenylmethane [7b,c] or benzene [5a–l,6a,b] units were used as the central aromatic platform in the construction of the receptor structures. The aromatic core has both the task of arranging the recognition units in such a way that a three‐dimensional recognition of the carbohydrate substrate is possible, and to enable the formation of CH⋅⋅⋅π interactions with the carbohydrate‐CH units.…”

“…These compounds have the potential to act as artificial receptors in analogy to the known receptors with a triethylbenzene‐, [5a–l,6a–b] biphenyl‐ [7a] or diphenylmethane‐based [7b,c] scaffold (Figure 2a–c). It is worth noting that the fluorene backbone (Figure 2d) combines the structural elements of both biphenyl and diphenylmethane scaffolds, as shown by markings in Figure 2.…”

Synthesis and crystal structures of two solvates of 1-{[2,6-bis(hydroxymethyl)-4-methylphenoxy]methyl}-3,5-bis{[(4,6-dimethylpyridin-2-yl)amino]methyl}-2,4,6-triethylbenzene

“…The possibilities for functionalization of acyclic and macrocyclic molecules of this type are manifold, allowing the synthesis of a whole range of compounds for systematic binding studies. Some examples of suitable functional groups, which can act as recognition units and have been considered in our studies, are heteroaromatic units such as pyridine-, pyrimidine- (Lippe et al, 2015), pyrazole- (Koch et al, 2016), purine- (Kaiser et al, 2019) or phenanthroline-based recognition groups (Ko ¨hler et al, 2020), (cyclo)alkylamino groups (Stapf et al, 2020a;Leibiger et al, 2022) as well as subunits containing hydroxy groups. Among the molecules with the latter groups, studies of the binding properties of acyclic (Mazik & Kuschel, 2008a) and macrocyclic (Amrhein et al, 2016) compounds bearing a hydroxymethyl group at the triethylbenzene core should be mentioned.…”