TY - JOUR
T1 - Polythiacrown macro- and gigantocycles with chiral diacetal cores
AU - Abramson, Sarah
AU - Berkovich-Berger, Dvora
AU - Dagan, Shai
AU - Goldberg, Israel
AU - Golender, Lara
AU - Grabarnik, Mikhail
AU - Lemcoff, N. Gabriel
AU - Weinman, Sarah
AU - Fuchs, Benzion
PY - 2007
Y1 - 2007
N2 - We present a unique class of polythiacrown macro- and gigantocyclic [9] systems, consisting of ethylene 1,2-dithioglycol (ETG) to poly(ethylene thioglycol) (ETGn) bridges over one to six diacetal units of the cis-1,3,5,7-tetraoxadecalin (TOD) type. The latter is a dissymmetric, chiral moiety, incorporating a cavity with built-in high electron lone pair concentration, serving as the "core" of chiral macrocyclic host systems with good inclusion ability of ions and polar molecules. We describe two approaches: (i) the reactions of the 2,6-bis(bromomethyl)-cis-TOD podand (6) with ETG or higher ETGns (12n), in Cs 2CO3 promoted processes, leading to the innate but uncontrolled formation of polythiacrown-TOD macrocycles having ETG/TOD ratios of 1:1 (7), 2:2 (8) and further 3:3-6:6 (11t/m)[10] macrocycles via open dithiol intermediates, and (ii) judicious preparation, using K2CO3, of oligomeric dibromide intermediates with ETGn:TOD ratios 1:2, 2:3 or 3:4 (14n/m), which led (with further ETGn) in a controlled way to the 2:2 (8n), or 3:3, 4:4 and 6:6 (1n/m) macro- and gigantocyclic systems. Altogether, the outcome of these processes depends on the relative concentrations of the reactants. Synthesis was accompanied by detailed (NMR and MS) spectroscopy. X-ray crystallographic analysis of a number of macrocycles, complemented by (MM & MD) computation, made possible valuable structural, stereochemical and conformational analysis. While sophisticated in their stereochemical features, these systems are readily prepared in enantiopure form and hold great promise of chemical reactivity in metal ion inclusion and molecular and chiral recognition.
AB - We present a unique class of polythiacrown macro- and gigantocyclic [9] systems, consisting of ethylene 1,2-dithioglycol (ETG) to poly(ethylene thioglycol) (ETGn) bridges over one to six diacetal units of the cis-1,3,5,7-tetraoxadecalin (TOD) type. The latter is a dissymmetric, chiral moiety, incorporating a cavity with built-in high electron lone pair concentration, serving as the "core" of chiral macrocyclic host systems with good inclusion ability of ions and polar molecules. We describe two approaches: (i) the reactions of the 2,6-bis(bromomethyl)-cis-TOD podand (6) with ETG or higher ETGns (12n), in Cs 2CO3 promoted processes, leading to the innate but uncontrolled formation of polythiacrown-TOD macrocycles having ETG/TOD ratios of 1:1 (7), 2:2 (8) and further 3:3-6:6 (11t/m)[10] macrocycles via open dithiol intermediates, and (ii) judicious preparation, using K2CO3, of oligomeric dibromide intermediates with ETGn:TOD ratios 1:2, 2:3 or 3:4 (14n/m), which led (with further ETGn) in a controlled way to the 2:2 (8n), or 3:3, 4:4 and 6:6 (1n/m) macro- and gigantocyclic systems. Altogether, the outcome of these processes depends on the relative concentrations of the reactants. Synthesis was accompanied by detailed (NMR and MS) spectroscopy. X-ray crystallographic analysis of a number of macrocycles, complemented by (MM & MD) computation, made possible valuable structural, stereochemical and conformational analysis. While sophisticated in their stereochemical features, these systems are readily prepared in enantiopure form and hold great promise of chemical reactivity in metal ion inclusion and molecular and chiral recognition.
KW - Chiral diacetals
KW - Crown compounds
KW - Macrocycles
KW - S ligands
KW - Tetraoxadecalins
UR - http://www.scopus.com/inward/record.url?scp=34250642789&partnerID=8YFLogxK
U2 - 10.1002/ejoc.200601045
DO - 10.1002/ejoc.200601045
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AN - SCOPUS:34250642789
SN - 1434-193X
SP - 1957
EP - 1975
JO - European Journal of Organic Chemistry
JF - European Journal of Organic Chemistry
IS - 12
ER -