Proton-ionizable crown compounds. 13. Synthesis and structural studies of crown compounds containing the triazole subcyclic unit and lipophilic substituents

Eight new macrocyclic polyether ligands containing the proton-ionizable triazole subcyclic unit have been prepared. Most of these compounds contain octyl, benzo or cyclohexano lipophilic groups. The unsubstituted triazolo-18-crown-6 ( 5 ) formed an unusual complex with silver ion. The crystal structure of this silver complex showed one crown complexed with one silver cation and two associated silver nitrate molecules. The new lipophilic triazolo-crowns are being tested as cation carriers for alkali and other metal cations in a bulk liquid membrane system.     

Proton-ionizable crown compounds. 4. New macrocyclic polyether ligands containing a triazole subcyclic unit

A series of macrocyclic polyether (crown) ligands containing the proton-ionizable s-triazole subcyclic unit were prepared by reacting the 1-THP blocked 3,5-bis(chloromethyl)-1H-1,2,4-triazole with various oligoethylene glycols. The starting bis(chloromethyl)triazole is a vessicant and must be used with caution. Triazolo-18-crown-6 ( 5 ) formed stable complexes with barium, strontium, copper and benzylammonium cations but not with potassium or lithium. The crystal structure of 5 showed the triazole proton to be on nitrogen 3 which is outside the macroring cavity.     

Proton-ionizable crown compounds. 3. Synthesis and structural studies of macrocyclic polyether ligands containing a 4-pyridone subcyclic unit

New proton-ionizable macrocyclic polyether ligands containing the 4-pyridone subcyclic unit have been prepared by reacting 4-THP blocked-2,6-pyridinedimethanol with various oligoethylene glycol ditosylates. The 18-crown-6 ligand containing the 4-pyridone subcyclic unit, 4 , forms stable complexes with alkali metal and organic ammonium cations. The crystal structure of 4 proves the 4-pyridone structural unit. The crystal structure of the potassium thiocyanate complex of 4 is also reported and shows the complex to contain the 4-hydroxypyridine unit.     

Proton-ionizable crown compounds. 11. Synthesis of macrocyclic ligands containing two sulfonamide groups and chloro substituents or pyridine subcyclic units and a preliminary study of cation transport by three of these ligands

Five new macrocyclic ligands each containing two sulfonamide groups have been prepared. Three of these compounds contain one or two chloro substituents and the other two have one or two pyridine subcyclic units. A seventeen-membered ring ligand (4) was found to be an excellent transport agent for all alkali metal cations in a water-methylene chloride-water bulk liquid membrane system when the pH of the source phase was 13 or higher. The chlorine-substituted analog (5) was a poor transport agent for the alkali metal cations possibly because the chlorine atom blocked entry to the macrocycle cavity. An open-chain analog containing two sulfonamide groups was particularly effective in transporting cesium ions.     

Proton-ionizable crown compounds. 19. The synthesis of chiral dialkyl-substituted triazolo-18-crown-6 macrocycles

Four new chiral macrocyclic polyether ligands containing the proton-ionizable triazole subcyclic unit have been prepared. The triazolo-crowns contain two isopropyl, two isobutyl, two (S)-sec-butyl or two benzyl substituents on chiral macro ring carbon atoms. A racemic triazolo-18-crown-6 containing two (1-naphthoxy)methyl substituents was also prepared.     

Proton-ionizable crown compounds. 10. Preparation and structural studies of macrocyclic ligands containing two sulfonamide units and with seventeen to twenty-six ring members

Eight new macrocylic ligands each containing two sulfonamide groups have been prepared. Six of these compounds have both the sulfur and nitrogen atoms of the sulfonamide units substituted with aromatic rings. The nitrogen atoms of the other two compounds have alkyl ring connections. X-ray crystal structure data were obtained for new macrocyclic compounds of 20 and 23 ring members. Each crystal structure showed two molecules in the asymmetric unit. Molecule A of 5 and both molecules of 7 exist in a compact conformation suggesting that they could wrap around a metal ion during complexation. Some of these compounds will be used as cation carriers in a bulk liquid membrane system.     

Proton-ionizable crown compounds. 9. Synthesis and structural studies of new 14-crown-4 compounds containing a pyridine or 4-pyridone subcyclic unit

Four new 14-crown-4 macrocyclic ligands containing either a pyridine or a 4-pyridone subcyclic unit have been prepared. Two of the 4-pyridono-crowns contained lipophilic hydrocarbon substituents. The starting octyl- and benzyl-substituted 4-oxa-1,7-heptanediols were prepared from the 2-octyl- or 2-benzyl-1,3-propane-diol. When the two substituted 4-oxa-1,7-heptanediols were treated with tosyl chloride, both the expected 2-substituted-4-oxaheptane-1,7-ditosylates and the ditosylate of the dimeric diol were isolated. X-ray structure determinations were carried out on two of the new 14-crown-4 compounds.     

Synthesis of macrocyclic acetals containing lipophilic substituents

A series of new macrocyclic acetals all containing lipophilic substituents were prepared by reacting the appropriate diols and lipophilic acetal-containing dichlorides or ditosylates. The reactions using the ditosylates gave the best yields. Several of the macrocycles contained pyridine subcyclic units. The lipophilic acetals were obtained by reacting a long-chain aldehyde with 2-hydroxyethyl chloride or tosylate and 3-hydroxypropyl chloride or tosylate. At least two of the new pyridino ligands complexed with metal ions as shown by the use of these materials as carriers for silver nitrate through a water-methylene chloride-water bulk liquid membrane system.     

Proton-Ionizable crown compounds. 7. Synthesis of new crown compounds containing the dialkylhydrogenphosphate moiety

A new series of macrocyclic ligands containing the dialkylhydrogenphosphate moiety is reported. These compounds were prepared by reacting phosphorus oxychloride with the appropriate oligoethylene glycol followed by a hydrolysis step. One of these new macrocyclic compounds transported the alkali metal cations as well as lead, zinc and silver ions.     

Proton-ionizable crown compounds. 12. Proton-Coupled selective membrane transport of Li+ using a proton-ionizable pyridono macrocycle

The macrocycle-mediated fluxes of several alkali metal cations have been determined in a H₂O-CH₂Cl₂-H₂O liquid membrane system. Water-insoluble proton-ionizable macrocycles of the pyridono type were used. The proton-ionizable feature allows the coupling of cation transport to reverse H⁺ transport. This feature offers promise for the effective separation and/or concentration of alkali metal ions with the metal transport being driven by a pH gradient. A counter anion in the source phase is not co-transported. The desired separation of a particular metal ion involves its selective complexation with the macrocycle, subsequent extraction from the aqueous phase to the organic phase, and exchange for H⁺ at the organic phase-receiving phase interface. Factors affecting transport which were studied include ring size, source phase pH, and receiving phase pH. Lithium was transported at a rate higher than that of the other alkali metals in both single and competitive systems using a 15-crown-5 pyridono carrier.     

Proton-Ionizable crown compounds. 8. Synthesis and structural studies of macrocyclic polyether ligands containing a 4-thiopyridone subcyclic unit

Three new proton-ionizable macrocyclic polyether ligands containing the 4-pyridone subcyclic group have been prepared. Two of these ligands contain lipophilic n-octyl substituents, the other ligand contains a phenyl substituent. The 15-crown-5 ligand containing both a 4-pyridone subcyclic unit and an n-octyl substituent selectively transported lithium cations in a water-methylene chloride-water bulk liquid membrane system. Five crown compounds containing the 4-pyridone subcyclic unit were converted to the 4-thiopyridono-crown compounds when treated with Lawesson's Reagent. The crystal structure of 4-thiopyridono-18-crown-6 shows a carbon-sulfur double bond and a molecule of water hydrogen bonded inside the macrocycle cavity.     

Reactions of aromatic and heteroaromatic compounds containing electron-acceptor substituents

A method was developed for the preparation of 4-chloromethyl-2-acylthiophenes and m-(chloromethyl)acylbenzenes in up to 65% yields by the action of paraformaldehyde and anhydrous aluminum chloride on the corresponding carbonyl compounds. The reaction mechanism is discussed.See [1] for communication XXII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1474–1476, November, 1978.     

Reactions of aromatic and heteroaromatic compounds containing electron-acceptor substituents

Synthetic methods based on accessible furan compounds of 5-benzyl(3-furyl)carbinol, a necessary component for the preparation of modified pyrethrins, were studied. The carbinol was obtained in 24% overall yield by a five-step synthesis starting from 4-bromofuran-2-carboxylic acid, for the preparation of which an improved method is proposed. Acylation of benzene with the chloride of the latter acid gave 4-bromo-2-benzoylfuran (in 77% yield), the reduction of which by the action of AlCl₃ + LiAlH₄ gave 4-bromo-2-benzylfuran (in 74% yield). The latter was treated with butyllithium and dimethylformamide to give 5-benzyl-3-formylfuran, which was converted to the carbinol in quantitative yield by the action of LiAlH₄.See [1] for communication XXI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 306–310, March, 1978.     

New one step synthesis of crown compounds containing a 1,3,4‐thiadiazole moiety

New macrocyclic polyether compounds containing a 2,5‐bis(2‐hydroxyphenyl)‐1,3,4‐thiadiazole moiety have been prepared by a nucleophilic substitution reaction involving ethylene or polyethylene glycol ditosylate and a bisphenol, the 2,5‐bis(2‐hydroxyphenyl)‐1,3,4‐thiadiazole, with solid anhydrous carbonate as a base. The structures of the macrocycles obtained were firmly established by ¹H and ¹³C nmr spectroscopy and their mass spectra.     

The synthesis of novel Schiff base bis- and tris- crown ether ligands containing recognition sites for alkali and transition metal guest cations

New Schiff base bis- and tris-benzo crown ether ligands containing recognition sites for alkali and transition metal guest cations have been prepared. Preliminary coordination studies of these ligands with sodium and copper(I) guest cations have led to the successful isolation of mono- and heteropolymetallic complexes.     

Synthesis and transport studies of new enantiopure lipophilic crown ethers containing a diarylphosphinic acid unit

The synthesis of new enantiopure lipophilic crown ethers (S,S)-6, (R,R)-6 and (S,S)-7 containing a diarylphosphinic acid unit has been carried out. The transport ability of these ligands has been studied in an aqueous source phase/lipophilic organic bulk liquid membrane/aqueous receiving phase system controlled by the pH of the media. The transport of metal ions and amines has also been studied. These studies showed high selectivity for protonated amines.     

Preparation of crown compounds containing allyloxymethyl or butenyl groups for attachment to silica gel or containing long chain lipophilic groups for use in liquid membrane systems

Several new macrocyclic polyether ligands have been prepared for use in the separation of metal ions from aqueous solutions. Four of the crown ethers reported contain 1,2,4-triazole or 4-pyridone protonionizable subcyclic units and lipophilic groups. The remaining crown ethers are not proton-ionizable but contain alkene groups and were prepared for attachment to silica gel. The crowns were prepared by reacting the appropriate glycols with the appropriate ditosylates or dichloride in the case of the 1,2,4-triazole subcyclic unit. The crowns with proton-ionizable and lipophilic substituents were tested in liquid membrane transport systems and some of the crowns with alloxymethyl or butenyl substituents were attached to silica gel. The log K values for the interaction of these silica gel-bound macrocycles with certain metal ions were nearly the same (± 10%) as those for the association of the unbound macrocycles with the same metal ions.