25423-56-7Relevant articles and documents
Crown Thioether Chemistry: Structural and Conformational Studies of Tetrathia-12-crown-4, Pentathia-15-crown-5, and Hexathia-18-crown-6. Implications for Ligand Design
Wolf, Robert E.,Hartman, JudithAnn R.,Storey, John M. E.,Foxman, Bruce M.,Cooper, Stephen R.
, p. 4328 - 4335 (1987)
Tetrathia-12-crown-4 (12S4) in the solid state adopts a square conformation with the sulfur atoms at the corners, to yield a structure derived from fusion at the terminal S atoms of two "bracket" units. This macrocycle crystallizes in the monoclinic system, space group Cc, with a = 13.028(7) Angstroem, b = 12.884(5) Angstroem, c = 14.493(7), (β = 108.18(4) deg, and Z = 8.Pentathia-15-crown-5 (15S5) assumes an irregular conformation generated from two bracket units by fusion at one S atom and connection of the remaining two terminal S atoms by a -CH2CH2- linkage.This crown thioether also crystallizes in the monoclinic system, space group P21/n, with a = 16.444(3) Angstroem, b = 5.432(1) Angstroem, c = 18.255(3) Angstroem, β = 115.58(1) deg, and Z = 4.Hexathia-18-crown-6 (18S6) adopts a conformation produced by connection of two bracket units by two -CH2CH2- linkages.It crystallizes in the orthorhombic system, space group Fdd/2, with a = 20.466(1) Angstroem, b = 32.222(3) Angstroem, c = 5.213(4) Angstroem, and Z = 8.Analysis of these structures reveals a pronounced preference for gauche placement at C-S bonds.This preference causes the ubiquity of bracket units and contrasts with the antipathy to gauche placement of the C-O bonds in oxa-crown ethers.This marked difference derives from the difference in C-E bond lenghts, which changes nonbonded 1,4-interactions in both C-C-E-C and E-C-C-E fragments.
SYNTHESIS OF 15- AND 18-MEMBERED POLYTHIAMACROCYCLIC LIGANDS
Pavlishchuk, V. V.,Strizhak, P. E.
, p. 553 - 555 (2007/10/02)
Reaction of 1,8-dimercapto-3,6-dithioactane with oxa-, aza-. and thiadihaloderivatives under high dilution conditions in the presence of cesium carbonate, which acts as a template for the condensation reaction, produces 15- and 18-membered polythiamacrocyclic ligands in yields greater than 50percent.
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.
