Dynamic combinatorial libraries of macrocycles derived from phthalic aldehydes and α,ω-diamines

Fast imine equilibration and its consequences for the evaluation of dynamic combinatorial libraries

“…11 Imination reaction has already been employed for the synthesis of macrocycles benefiting from the DCC paradigm by several groups. [12][13][14][15][16][17][18] Recently, 19 we described protocols allowing quick "freezing" of the primary library of imines into the corresponding secondary library of amines by means of NaBH 4 reduction. It is obvious that an accurate evaluation of the effect of a particular template requires that the equilibration time of the library must be much longer than the time needed for "freezing" the reaction or, in general, than the time of all the steps in the protocol used to measure the library composition.…”

Selective Host Molecules Obtained by Dynamic Adaptive Chemistry

“…The nontemplated DCL indicated formation of [2+2] and [3+3] macrocycles as major components, while addition of one equivalent of Na + yielded the [1+1] macrocycle almost exclusively. Interesting results were also obtained with the DCLs formed from isophthalic aldehyde 6 and diamines 5 a and 5 b in the presence of potassium ions 20. Addition of two equivalents of KClO 4 to the nontemplated DCLs, which contain only the [2+2] macrocycle in both cases, shifted the equilibrium to the exclusive formation of the [3+3] macrocycle in the case of the DCL formed from 6 and 5 a and determined the amplification of the [3+3] (17 %) and [4+4] (14 %) macrocycles in the case of the DCL formed from 6 and 5 b .…”

“…Interesting results were also obtained with the DCLs formed from isophthalic aldehyde 6 and diamines 5 a and 5 b in the presence of potassium ions. [20] Addition of two equivalents of KClO 4 to the nontemplated DCLs, which contain only the [2+2] macrocycle in both cases, shifted the equilibrium to the exclusive formation of the [3+3] macrocycle in the case of the DCL formed from 6 and 5 a and determined the amplification of the [3+3] (17 %) and…”

“…The clipping reaction employed to form the macrocycles is a [2+3] condensation between 2,2'-(ethylenedioxy)diethylamine and 1,3,5-benzenetrialdehyde to form a macrobicycle. The power of imine DCC for obtaining new interlocked structures was illustrated by Stoddart et al [72c] in the high yield synthesis (88-98 %) of [n]rotaxanes (n = 3-5, 8, 12,16,20) of type 50 ( Figure 11) by one-pot clipping of up to 20 macrocycles, around ÀCH 2 NH 2 + CH 2 À recognition units incorporated in the linear dumbbell. The efficiency of the reaction was explained by a positive cooperativity between the forming macrocycles, the whole system being stabilized by p-p interactions between aromatic units of the macrocycles.…”

Efficient Construction and Structure Determination of Novel Macrocycles with Calixarene Bishydrazones

“…[7][8][9][10][11][12][13][14][15] In this field the synthesis and applications of Schiff-base macrocycles have been of great importance in macrocyclic, coordination and supramolecular chemistry. [16][17][18] The combination of calixarene and salen results in a novel family of calixsalen type macrocycles. [19,20] The condensation reactions of previously designed diaminocarlixarenes as polyamines with diformylcarlixarenes as dicarbonyl compounds provided a useful tool toward obtaining a broad variety of macrocyclic calixarene Schiff bases.…”