Rapid access to C ₃- and C _s-symmetric AAT organogelators via ring opening of a common benzotrifuranone precursor

Abstract

2010) Rapid access to C 3 -and C s -symmetric AAT organogelators via ring opening of a common benzotrifuranone precursor, Supramolecular Chemistry,[789][790][791][792][793][794][795][796][797][798][799][800][801][802] Presented is a rapid and general approach to functionalised 1-aza-adamantanetrione (AAT) donor-s-acceptor molecules from a phloroglucinol-derived trilactone, benzotrifuranone (BTF). Ten C 3 -symmetric AATs bearing diverse aryl amide substituents are accessed in two synthetic steps: (1) the exhaustive ring opening of BTF with aromatic amine nucleophiles (performed in up to 91% yield) and (2) cyclisation with hexamethylenetetramine (performed in up to 75% yield). Additionally, stepwise ring opening of BTF allows synthesis of phloroglucinol intermediates with two unique aryl amide substituents and ultimately C s -symmetric AATs. Of the novel AATs prepared, three (including the C s -symmetric hybrid) are effective gelators of chlorinated solvents (critical gelation concentration (CGC) ¼ 0.2 -0.4 wt%) and one, with naphthyl substituents, forms translucent gels from aromatic solvents (CGC , 0.3 wt%). The combination of AATs with moderately electron-poor and electron-rich aromatic substituents results in functional complementarity and gelation at concentrations below what is required for the individual components. Electron microscopy of the gel morphologies shows high aspect ratio fibres underlying the gel network superstructures in most cases. Polarised optical microscopy has allowed imaging of representative native organogel phases, and reveals striking morphology differences between gels that also share different optical and/or thermal stability properties.

Functional π-Gelators and Their Applications

“…In cyclohexane, 274a formed a gel with β-sheet architecture and spherulitic networks in chloroform/petroleum ether whereas 274b self-organized to form intertwined nanobelts in chloroform, and crystalline microbelts in acetone and alcohols. The C 3 symmetric 1-aza-adamantanetrione containing naphthalene 275 (Chart ) formed translucent gels consisting of lamellar sheet architectures with layers of uniform thickness . Compound 276 (Chart ) formed organogels in cyclohexane with enhanced CD signals in the gel phase. , Coassembled gels of 276 and a nitrobenzofurazan derivative showed efficient energy transfer at different D–A ratios …”

“…The C 3 symmetric 1-aza-adamantanetrione containing naphthalene 275 (Chart 67) formed translucent gels consisting of lamellar sheet architectures with layers of uniform thickness. 637 Compound 276 (Chart 67) formed organogels in cyclohexane with enhanced CD signals in the gel phase. 638,639 Coassembled gels of 276 and a nitrobenzofurazan derivative showed efficient energy transfer at different D−A ratios.…”

Seven‐Membered Intramolecular Hydrogen Bonding of Phenols: Database Analysis and Phloroglucinol Model Compounds

“…Subsequent demethylation using BBr 3 at low temperature provided the phloroglucinol targets 4a and 4b in excellent yield. To generate a small library of model compounds 5 , we have capitalized on the versatile aminolysis chemistry of benzotrifuranone (BTF) 8 5e–5g (Table 5). Shown is the treatment of BTF with various aliphatic ( a – e ) and one aromatic ( f ) amines; the former include primary ( a ), branched/chiral ( b ), secondary acyclic ( c ), and secondary cyclic ( d and e ) derivatives that subtly vary the H‐bond accepting ability of the amide carbonyl.…”

“…CI‐MS spectra were recorded with a Thermo Scientific Trace GC DSQ (single quadrupole) spectrometer. Compounds 6 5a and 8 5e–5g were prepared as described in the literature.…”

Tuning Supramolecular Polymer Assembly through Stereoelectronic Interactions

“…Over the last 20 years, it has been appreciated that certain stereoelectronic interactions, such as the n → π* interaction, can act to stabilize the folded states of polypeptides − and modulate the reduction potentials of strained disulfide bonds in natural products . Moreover, intramolecular stereoelectronic interactions, as we showed years ago using 1-aza-adamantanetrione donor−σ–acceptor molecules, can serve as a significant driving force for intermolecular self-assembly. − Herein, we present an example of an intramolecular n → π* interaction which acts as a secondary effect to alter the assembly strength of an intermolecularly hydrogen bonded supramolecular polymer.…”