Eine neue, bequeme [2.2]‐Kronenether‐Synthese; Vergleich verschiedener Detosylierungsmethoden

Buhleier, Gon; Raßhofer, Werner; Wehner, W.; Luppertz, Friedhelm; Vögtle, Fritz

doi:10.1002/jlac.197719770812

Cited by 27 publications

(4 citation statements)

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“…Different methods to remove the iV-tosyl blocking groups were tried, including HBr/phenol, H2S04, LiAlH4/THF, and NaAlH2(OCH2CH2OCH3)2. 164 The yields of this last step varied as a function of the number of tosyl groups and the size of the macrocycle. With a triaza-12-crown-4, it was found that HBr/phenol was the best detosylating reagent followed by H2S04 and LiAlH4.…”

Section: A°w°amentioning

confidence: 99%

“…With a triaza-12-crown-4, it was found that HBr/phenol was the best detosylating reagent followed by H2S04 and LiAlH4. 164 Tabushi and co-workers reported a general synthetic procedure to prepare the polyaza-crown compounds by reacting a polyamine and the dimethyl ester of an oligoglycolic acid followed by reduction of the resulting cyclic diamide (method AH).136,137-178 This method uses…”

Section: A°w°amentioning

confidence: 99%

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Synthesis of aza-crown ethers

Krakowiak¹,

Bradshaw²,

1989

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Section: A°w°amentioning

confidence: 99%

Section: A°w°amentioning

confidence: 99%

Synthesis of aza-crown ethers

Krakowiak¹,

Bradshaw²,

1989

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“…Lithium aluminum hydride is reported to be an effective reagent for sulfonamide removal (25), but it is inappropriate for 8 or 10 as the carboxamides would undergo reduction as well. Dissolving metal reductions using sodium amalgam (15,21,26), or Li or Ca (21) in liquid ammonia, are other reductive cleavage reagents.…”

Section: Ligand Synthesismentioning

confidence: 99%

Polycarboxylate diaza crown ethers derived from R,R-(+)-tartaric acid: synthesis and complexation of metal ions

Anantanarayan¹,

Fyles²

1990

Can. J. Chem.

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ASHOK ANANTANARAYAN and THOMAS M. FYLES. Can. J. Chem. 68, 1338 (1990.The synthesis and complexation properties of polycarboxylate diaza crown ethers based on R,R-(+)-tartaric acid are described. Cesium carbonate mediated macrocyclization of a bis-tosylamide precursor with a bis-tosylate precursor provided the protected crown ethers. Photochemical deprotection of the tosylamides and hydrolysis of the carboxamides yielded dicarboxylic and tetracarboxylic acid derivatives of 1, lO-diaza-18-crown-6. N-Methylenecarboxylate (N-acetate) derivatives were prepared by N-alkylation with bromoacetic acid. The synthetic and purification procedures developed provide samples of the ligands in a metal-free form. Acidity and stability constants for complexation of alkali metal, alkaline earth, late-and post-transition metal cations were determined by potentiometric titration. The ligands form complexes which show enhancement of stability by charge-charge and chelate interaction with the carboxylates. In comparison with crown ether polycarboxylates these aza crown ethers showed a selectivity for softer metal ions relative to alkali and alkaline earth metal ions. N-Methylenecarboxylate chelate ligands were found to bind almost all types of metal ions, due to a highly co-operative array of charge-charge, chelate and crown ether interactions. Metal ion recognition by synthetic and naturally occurring ligands is a complex process involving a cooperative match of the complementary properties of the host and the guest. A key factor in the design of new ligands with unique complexation behaviors is the choice of ligand donor sites (1). Within a class of ligands, such as the crown ethers or cryptands, clear changes in selectivity of cation binding are provoked by substitution of the oxygen donors of a parent ring system for nitrogen or sulfur donor sites (2). Such substitutions alter the primary character of the donor (Lewis basicity) as well as the geometrical and conformational properties of the ligand (3). Thus in a system involving highly cooperative binding interactions, donor atom substitution can profoundly influence binding selectivity.Our interest in ligand design has centered on crown ethers derived from R,R-(+)-tartaric acid: the di-, tetra-, and hexaacids illustrated at the top of Fig. 1 (4-6). The tartarate derived units impart rigidity to the ligands, leading to well defined conformations, and the carboxylates, when ionized, provide a strong electrostatic field which greatly enhances complex stability for alkali metal and alkaline earth cations. Despite the favorable Coulombic interactions, binding of heavy metal cations occurs only to a limited extent due to a mismatch of the hard oxygen donor set and the softer guest cations (6). An obvious ligand modification which might lead to stabilized crown ether type complexes of heavier cations would be the substitution of some of the donor atoms for N or S. We have previously reported dithia crown ethers bearing four carboxylates (7); the purpose of this report is to describe th...

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“…(Bergman andBrynolf, 1989) 82, 115, 708, 720, 751 Brzezinska, E. (Brzezinska and Glinka, 1986) 456, 467 Brzozka, Z. 303, 345 Buhleier, E. (Buhleier et al, 1977) 158, 159, 160, 163, 164, 167, 253, 341; 336, 341; (Buhleier et al, 1977) 358, 368, 397; (Buhleier et al, 1978) 394, 397, 435,467 Bujewski, A. (Biernat et al, 1979) 45, 66, 137, 166, 418, 420, 452, 453, 467, 515, 527, 528,534 49, 63, 69;(Martinet al, 1982) 49, 70, 129, 130, 146, 170;(Martin and Bulkowski, 1982) 131, 170;(Martinet al, 1982) 359, 399;(Bulkowski et al, 1977) 473, 533, 534; 553, 688; 667, 668, 682; (Martin and Bulkowski, 1982) 667, 668, 688 (Izatt and Christensen, 1978) 4, 25;(Izatt and Christensen, 1987a) 4, 1 I , 25; (Izatt and Christensen, 1987b) 4, 1 I , 25; ; (Bradshaw et a]., 1989b) 20, 23; (Bradshaw et al, 1976) 31, 66; Christensen, J .…”

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confidence: 99%

Author Index

1993

Chemistry of Heterocyclic Compounds: A Series of Monographs

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Eine neue, bequeme [2.2]‐Kronenether‐Synthese; Vergleich verschiedener Detosylierungsmethoden

Cited by 27 publications

References 4 publications

Synthesis of aza-crown ethers

Synthesis of aza-crown ethers

Polycarboxylate diaza crown ethers derived from R,R-(+)-tartaric acid: synthesis and complexation of metal ions

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