Synthesis, Structure, and Functionalization of Homo Heterocalix[2]arene[2]triazines: Versatile Conformation and Cavity Structures Regulated by the Bridging Elements

Abstract

A number of homo[2] and homo[4] heterocalix[2]arene[2]triazines were synthesized through a general and good-yielding fragment coupling approach starting from cyanuric halides, aromatic and aliphatic diols, and diamines under very mild reaction conditions. While homo[2] tetraazacalix[2]arene[2]triazine gave a twisted and pinched 1,2-alternate conformer, almost all homo[2] heterocalix[2]arene[2]triazines adopted different partial cone conformations in the solid state. Homo[4] heterocalix[2]arene[2]triazines yielded more diverse conformational structures including partial cone, pinched partial cone, 1,2-alternate and twisted 1,2-alternate, depending on the nature of bridging moieties. On the basis of (1)H NMR spectra, homo[2] and homo[4] heterocalix[2]arene[2]triazines were fluxional macrocycles in solution, and they underwent rapid conformation interconversion at different temperatures. Efficient and straightforward nucleophilic aromatic substitution reaction and palladium-catalyzed cross-coupling reactions on chlorotriazine rings, and the nucleophilic alkylation reaction on the bridging nitrogen atoms led to the construction of various highly functionalized homo heterocalix[2]arene[2]triazine derivatives.

Frustrierte Helizität: Zusammenführung divergierender Enden einer stabilen aromatischen Amid‐Helix zu einem fluxionalen Makrocyclus

“…Die Struktur und das Verhalten von 3 stehen in Verbindung mit einigen bekannten fluxionalen Makrocyclen [19][20][21] oder achtfçrmigen Molekülen, [21,22] die aus Metallkomplexen [20] oder aus erweiterten Porphyrinen abgeleitet sind. [21,22] Sie stehen im Kontrast mit den meisten aromatischen makrocyclischen Oligoamiden, die strukturbeständige planare Strukturen bilden, was die bevorzugten lokalen Konformationspräferenzen erfüllt und die helikale Faltung in nicht-cyclischen Molekülen unterstützt.…”

“…Zusätzlich wäre eine nicht-fluxionale Umkehrung der Händigkeit mit P i <=> M i denkbar.U mf estzustellen, ob und welche dieser Mechanismen vorherrschen, wurde mithilfe von molekulardynamischer Simulationen gearbeitet. Insbesondere wurden Inversionsbahnen mit einer Dauer von 10 msv orgetäuscht, entweder durch simuliertes Glühen, d. h. Heiz-Kühl-Zyklen zwischen 300 000 und 800 K, oder mithilfe von metadynamischen Simulationen [5,18] Die Struktur und das Verhalten von 3 stehen in Verbindung mit einigen bekannten fluxionalen Makrocyclen [19][20][21] oder achtfçrmigen Molekülen, [21,22] die aus Metallkomplexen [20] oder aus erweiterten Porphyrinen abgeleitet sind. [21,22] Sie stehen im Kontrast mit den meisten aromatischen makrocyclischen Oligoamiden, die strukturbeständige planare Strukturen bilden, was die bevorzugten lokalen Konformationspräferenzen erfüllt und die helikale Faltung in nicht-cyclischen Molekülen unterstützt.…”

Fluorinated Triazines

“…It is known [ 88 ] The ability of fl uorine atoms in cyanuric fl uoride 55 to be replaced by action of O-nucleophiles can be exploited for the synthesis of calix [2]arene- [2]triazines 146 and 147 [ 89 ]. The reaction of 55 with 1,3-phenylenedimethanol leads to the formation of fl uoro compound 145 , and then to calix 146 .…”

Effective asymmetric Michael addition of anthrone to nitroalkenes using chiral tetraoxacalix[2]arene[2]triazines as organocatalysts

“…The form of the bridging heteroatoms, namely, cooperation of the steric, conjugative, and electronic features for the atoms of nitrogen and oxygen, manages cavity dimensions greatly, which generates a group of precisely set cavities where the distance between two benzene rings at the upper rim varies between 5.011 and 7.979 Å. The easiness of planning and more advanced chemical modification and the promptly adjustable cavity constructs make such aza‐ and/or oxo‐bridged calix[2]arene[2]triazines unmatched fields for studying supramolecular chemistry …”

“…The easiness of planning and more advanced chemical modification and the promptly adjustable cavity constructs make such azaand/or oxo-bridged calix [2]arene [2]triazines unmatched fields for studying supramolecular chemistry. [8][9][10][11][12][13] Anthrone generally serves as a reactive diene when a combination of an alkali and dienophiles is present, affording the necessary Diels-Alder adducts in high yields instead of the Michael addition adducts. [14][15][16][17][18] It was reported that the Michael adducts were produced as side products in only a few cases in Diels-Alder reactions.…”