Synthetic and NMR Studies on Calix[n]Arene (n = 4,6,8) Triflates,Mesylates, and Tosylates |
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| Authors: | Zsolt Csók Gábor Szalontai Gábor Czira László Kollár |
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| Institution: | 1. University of Veszprém, Department of Organic Chemistry , H-8200 Veszprém, P.O. Box, 158, Hungary;2. University of Veszprém, NMR Laboratory , H-8200 Veszprém, P.O. Box, 158, Hungary;3. Central Research Institute of Chemistry of the Hungarian Academy of Sciences , H-1525 Budapest, P.O. Box, 17, Hungary;4. Janus Pannonius University, Department of Inorganic Chemistry , H-7601 Pécs, P.O. Box, 266, Hungary |
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| Abstract: | Abstract The synthesis and full characterization of eight new calixn]arene sulfonate esters including their conformational analysis were carried out. While p-tBucalix6]arene and p-tBu-calix8]arene esters are conformationally labile in the temperature interval of 25–100°C, p-tBu-calix4]arene mono-and diesters were isolated as stable conformers at ambient temperature. Two 1,3-functionalised compounds of these derivatives, p-tert-butylcalix4]arene ditriflate (5) and dimesylate (6) were shown unexpectedly high conformational stability up to 100°C by dynamic NMR measurements. The NMR measurements confirm the pinched-cone conformation for both derivatives. For the dealkylated calix4]arene derivatives the partial cone conformer of the triesters have been obtained as major products in all cases. |
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| Keywords: | Calixarene sulfonate esters ‘pinched cone’ conformation NMR |
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