6 + 6 Macrocycles derived from 2,6-diformylpyridine and trans-1,2-diaminocyclohexane

Internal Hydrogen Bond Influences the Formation of [2+2] Schiff Base Macrocycle: Open‐Chain Vs. Hemiaminal and Macrocycle Forms

“…[19][20][21][22] The condensation of DFP with racemic DACH, run in boiling methanol (338K) and in the absence of any templating agent, leads to [2+2] imine 1(CH) accompanied with its 4+4 homologue. [19][20][21][22] The condensation of DFP with racemic DACH, run in boiling methanol (338K) and in the absence of any templating agent, leads to [2+2] imine 1(CH) accompanied with its 4+4 homologue.…”

“…[23][24][25][26][27][28][29][30][31][32][33][34][35][36] It should be emphasized that the 1,2-cycloalkyldiamines (especially trans-1,2-diaminocyclohexane) were studied in detail in the formation of ([2+2]) imine macrocycles scrutinizing the role of chirality of conformational preorganization. [19][20][21][22] tion. What does not raise doubts are three stages of the reaction, i.e.…”

“…[44] Again, for the reaction between benzaldehyde and 4-amine-4H-1,2,4-triazole quantum chemical topology methods revealed that the detachment of the [OH] fragment precedes the H′ transfer in N-H′···O bridge ((f ) in Scheme 2), the final step leading to H 2 O formation. [19][20][21][22] The not-templated synthesis of the macrocycle product is possible, however the outcome of the reaction strongly depends on the experimental conditions. Interestingly, between the CO bond dissociation and the NH′/OH′ bonds alteration, the latter roughly coinciding with the maximum of the energy barrier, there is a relatively long part of the reaction path whose crossing requires some one third of the energy barrier.…”

“…As examples of such dynamic libraries one can mention reactions possible within 2,6-diformylpyridine (DFP)/trans-1,2-diaminocyclohexane (DACH) and 2,6-diformylpyridine (DFP)/ trans-1,2-diaminocyclopentane (DACP) systems. [19][20][21][22] The condensation of DFP with racemic DACH, run in boiling methanol (338K) and in the absence of any templating agent, leads to [2+2] imine 1(CH) accompanied with its 4+4 homologue. Both imine products of alternating RRSS and RRSSRRSS chiralities of diamine units [19,20] have meso type structures.…”

“…Non-templated condensation of 2,6-diformylpyridine (DFP) and racemic trans-1,2-diaminocyclopentane (DACP), or racemic trans-1,2-diaminocyclohexane (DACH). [19][20][21][22] tion. While the second stage, consisting of some conformational changes, seems to be rather trivial, the hemiaminal synthesis and water elimination steps are more complicated as both involve N···H···O proton transfer and either NC bond formation (the former process) or CO bond dissociation (the later one).…”