24194-61-4Relevant articles and documents
A novel synthesis of cyclic polythioethers using liquid-liquid phase-transfer catalysis
Takido, Toshio,Toriyama, Masaharu,Ogura, Kazuhiro,Kamijo, Haruo,Motohashi, Shigeyasu,Seno, Manabu
, p. 1295 - 1301 (2003)
The synthesis of cyclic polythioethers has been achieved by the reactions of dithiols with alkyl dihalides. Thiols are not only hard to handle owing to their unpleasant smell, but also they are easily oxidizable, thus it is not easy to obtain various dithiols. However, we have developed a procedure for the preparation cyclic polythioethers by the reaction of dithioiminium salts with alkyl dihalides using phase-transfer catalyst without the use of dithiols, and have examined the ion recognition of these compounds.
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Rosen,Busch
, p. 148 (1969)
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Enhanced nickel(II) chelation by gew-dimethyl-substituted macrocyclic tetrathioethers
Desper, John M.,Gellman, Samuel H.,Wolf Jr., Robert E.,Cooper, Stephen R.
, p. 8663 - 8671 (2007/10/02)
The conformational and Ni(II)-binding properties of 1,4,8,11-tetrathiocyclotetradecane (1) and derivatives bearing gem-dimethyl pairs at the 6- or at the 6- and 13-positions (2 and 3, respectively) are compared. The syntheses and crystal structures of 2, 3, and their Ni(ClO4)2 complexes are reported; analogous data for I and its Ni(BF4)2 complex have been in the literature for some time. All three Ni(II) complexes show very similar 14-membered ring conformations, but the metal-free macrocycles display different conformations, in the solid state. These structural data suggest that each gem-dimethyl pair progressively biases the macrocycle toward the chelating conformation. We have examined the relative Ni(II) affinities of 1-3 in CD3NO2 by means of competition experiments monitored by 1H NMR. Tetrathioether 2 binds Ni(II) approximately 7.3 times more tightly than does 1 at room temperature, and 3 binds Ni(II) approximately 49 times more tightly than does 1. Thus, each gem-dimethyl pair leads to a 1.1 kcal/mol improvement in Ni(II) binding free energy under these conditions. We suggest that the incremental improvement in binding strength across the series 1-3 is correlated to the incremental changes in macrocycle conformation observed in the crystal structures of the metal-free thioethers.
Synthesis of Sulfur-Containing Macrocycles Using Cesium Thiolates
Buter, J.,Kellogg, Richard M.
, p. 4481 - 4485 (2007/10/02)
In dimethylformamide (DMF) solution 1,ω-dithiols are deprotonated by cesium carbonate.Reaction with 1,ω-dibromide in the same solvent leads to excellent yields of the corresponding macrocyclic (di)sulfides.The reaction is normally carried out by adding the dithiol (4x1E-2 M in DMF) and dibromide (4x1E-2 M in DMF) simultaneously to a 10percent excess of cesium carbonate (8.8x1E-3 M suspended in DMF) at 45-50 deg C over a period of 12-15 h.In this fashion there was obtained, for example, 1,12-dithiacyclodocosane (1d) in 85percent yield from the reaction of decane-1,10-dithiol with 1,10-dibromodecane.Other compounds obtained from the combination HS(CH2)mSH and Br(CH2)nBr are 1a (m=3, n=4), 1b (m=n=5), 1c (m=5, n=10), 1e (m=10, n=16), 1f (m=n=10), and 1g (m=16, n=18) in yields ranging from 45 to 90percent.By means of the same approach using various 1,ω-dithiols and o-xylene α,α'-dibromide, a series of macrocycles was prepared in yields ranging from 64-88percent.Various thia crown ether compounds have been prepared as well as ligands like 1,4,8,11-tetrathiacyclotetradecane (15), prepared from 3,7-dithianonane-1,9-dithiol and 1,3-dibromopropane in 76percent yield as compared to the literature yield of 7.5percent.This ability of cesium to promote ring closure appears to be unique certainly in cases where long chains devoid of heteroatoms are involved.This method makes available a variety of sulfur-containing ligands and the potential for scaling up the reaction has also been demonstrated.
