NMR and X-ray analysis of 25,27-dimethoxythiacalix[4]arene: unique infinite channels in the solid state

Lhoták, Pavel; Kaplánek, Lukáš; Stibor, Ivan; Lang, Jan; Dvořáková, Hana; Hrabal, Richard; Sýkora, Ján

doi:10.1016/s0040-4039(00)01696-8

Cited by 42 publications

(36 citation statements)

References 9 publications

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“…For the systematic study of the conformational behaviour of thiacalixarenes, a series of tetraalkylated and partially alkylated compounds 18Ϫ23 and 26Ϫ28 were prepared by this method. [16,17] The derivative 24 was synthesized [18] by the alkylation of 13 with the corresponding tosylate, and 25 was obtained by using chloroacetone as the alkylating agent. [19] Very recently, more sophisticated systems based on thiacalix [4]arene have been reported.…”

Section: Lower Rim Derivatization -Shaping Of the Molecular Skeletonmentioning

confidence: 99%

“…Moreover, compound 27 exhibits very interesting molecular packing. [17] The thiacalix [4]arene molecules are arranged along the x axis in such a way that they create infinite channels held together by intermolecular πϪπ interactions between the aromatic parts (upper rims) of the methoxy-substituted rings. The average distance between the two coplanar rings is 3.41 Å (Figure 8, a and b).…”

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Chemistry of Thiacalixarenes

2004

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Thiacalixarenes — new members of the calixarene family — are very promising molecules with many potential applications in supramolecular chemistry. The presence of four sulfur atoms in the place of methylene groups imparts many novel features and properties to these molecules. This review deals with the chemistry of thiacalixarenes, and by comparision with “classical” calixarenes, emphasizes their differences in reactivity, unusual conformational preferences and modified complexation abilities. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Section: Lower Rim Derivatization -Shaping Of the Molecular Skeletonmentioning

confidence: 99%

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Chemistry of Thiacalixarenes

2004

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“…8 The complexation properties of thiacalix [4]arenes can be altered, both by functionalizing the lower rim with ligating sites or by oxidation of the bridging sulfur atoms. [9][10][11][12] The groups of Vicens 13 and Bitter 14 have reported the synthesis of the diametrically substituted thiacalix [4]biscrowns-5 and -6. To the best of our knowledge only two proximally bridged thiacalix [4]crowns have been reported; a cyclic phosphorous diester amide and a lactone.…”

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Cation control on the synthesis of p-t-butylthiacalix[4](bis)crown ethers

Leeuwen¹,

Beijleveld²,

Kooijman

et al. 2002

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Abstract-Bridging of p-t-butylthiacalix[4]areneUnsubstituted thiacalix [4]arene is able to complex various transition metals, due to the presence of the bridging sulfur atoms. 7 The participation of sulfur in the complexation has been observed in X-ray crystal structures of complexes with alkali metal cations. 8 The complexation properties of thiacalix[4]arenes can be altered, both by functionalizing the lower rim with ligating sites or by oxidation of the bridging sulfur atoms. With 4 equiv. of Cs 2 CO 3 after 6 h, reaction of 1 with 2 (1.8 equiv.) exclusively afforded the 1,2-alternate thiacalix[4]biscrown-4 4 in 72% yield upon precipitation of the crude reaction mixture with methanol/acetone. Also the reaction of 1 and 3 (1.8 equiv.) with 4 equiv. of base gave a fast reaction (12 h, 100% conversion). The reaction gave a mixture of the 1,2-alternate thiacalix[4]biscrown-5 5 and the corresponding 1,3-alternate isomer 6. The pure thiacalix[4]biscrown-5 isomers 5 (27%) and 6 (15%) were isolated by fractional precipitation from methanol/acetone mixtures. Surprisingly, the proximal thiacalix[4]biscrowns-4 and -5 were only obtained in the 1,2-alternate conformation. The corresponding proximally substituted thiacalix[4]monocrown and proximally substituted cone thiacalix[4]biscrown compounds could not be detected. Compounds 4 and 5 were characterized by NMR ( 1 H and 13 C) and MS. 20,21 Definite proof for the 1,2-alternate thiacalix[4]biscrown-5 5 was obtained by an X-ray crystal structure (Fig. 1).22

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“…This approach was used for the synthesis of 1,3 disubstituted (so called dis tally substituted) derivatives 3-7 in 50-85% yields. 9-11 R = Me (3), CH 2 COOEt (4), CH 2 COOH (5), CH 2 Ph (6), CH 2 C 6 H 4 NO 2 (7), (CH 2 ) n Y (8), CH 2 COPh (9) Another approach is based on the creation of steric hindrances at the reaction centers by using reagents with bulky substituents. This approach was successfully used for the synthesis of a series of distal thiacalix [4]arenes 8 having the cone conformation in yields from 29 to 89% by the Mitsunobu reaction.…”

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Unusual functionalization of the lower rim of thiacalix[4]arene: competition of alkylation and transalkylation

et al. 2011

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Thiacalix[4]arenes mono , 1,3 di , tri , and tetrasubstituted at the lower rim, including those containing different substituents, were synthesized by the method based on the ability of the phenacyl moiety to serve as the protecting group, as well as to be involved in transalkylation.Thiacalix[4]arenes 1 represent a group of macrocyclic compounds with distinct molecular cavities 1-6 and serve as convenient molecular platforms for the design of preor ganized structures and supramolecular ensembles due to a considerable potential for modifications of the upper and lower rims of the macrocycle. The efficiency and se lectivity of guest-host interactions can be increased man ifold by the selective functionalization with appropriate heteroatomic groups as a result of the formation of recep tor systems containing several spatially preorganized bind ing sites. The existence of several stereoisomers of the thiacalix[4]arene platform, such as cone, partial cone, 1,3 and 1,2 alternates, 1 provides additional possibilities for the design of molecular receptors. In addition, the presence of bridging sulfur atoms and an increase in the size of the cavity of the macrocycle in thiacalix[4]arene 1 compared to calix[4]arene 2 results in new features in the chemical behavior, including the complexing ability. 4-6 Results and DiscussionIt is known that the reactions of calix[4]arene 2 with alkylating agents in the presence of alkali carbonates af ford disubstituted derivatives in high yields, whereas tetra substituted products are difficult to synthesize even with the use of strong bases, for example, of sodium hydride. 1-3 In the series of thiacalix[4]arenes, tetrasubstituted prod ucts are formed even in the presence of alkali carbonates. Hence, the development of approaches to the synthesis of partially substituted derivatives is of great importance.Such a different behavior of these metacyclophanes is due to changes in the hydrogen bond energy 7 and the acid base properties of phenol groups 8 at the lower rim of the macrocycles. In our opinion, there are three fundamen tally different approaches to the synthesis of partially sub stituted thiacalix[4]arenes. One approach is based on the optimization of the reaction conditions, including most often the use of stoichiometric amounts of the reagents and a base and the choice of the solvent, in which the intermediates of the reaction are removed from the reac tion zone due to their low solubility. This approach was 1: X = S, R = H 2: X = CH 2 , R = H

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NMR and X-ray analysis of 25,27-dimethoxythiacalix[4]arene: unique infinite channels in the solid state

Cited by 42 publications

References 9 publications

Chemistry of Thiacalixarenes

Chemistry of Thiacalixarenes

Cation control on the synthesis of p-t-butylthiacalix[4](bis)crown ethers

Unusual functionalization of the lower rim of thiacalix[4]arene: competition of alkylation and transalkylation

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