Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/95049
Title: Synthesis and conformational study of the first dithia[3]metacyclo[3](2,4)pyrrolophane and [2]metacyclo[2](2,4)pyrrolophane. 1H NMR spectroscopic evidence for a novel hydrogen-bonding phenomenon
Authors: Lai, Y.-H. 
Mok, K.F. 
Ting, Y.
Issue Date: 1994
Citation: Lai, Y.-H.,Mok, K.F.,Ting, Y. (1994). Synthesis and conformational study of the first dithia[3]metacyclo[3](2,4)pyrrolophane and [2]metacyclo[2](2,4)pyrrolophane. 1H NMR spectroscopic evidence for a novel hydrogen-bonding phenomenon. Journal of Organic Chemistry 59 (24) : 7341-7345. ScholarBank@NUS Repository.
Abstract: The first examples of a dithia[3]metacyclo[3](2,4)pyrrolophane and a [2]metacyclo[2](2,4)-pyrrolophane, namely 3g and 4g, respectively, were synthesized. The dithiacyclophane 3g was found to adopt the syn conformation both in solid state and in solution. Results from the 1H NMR spectroscopic study of 3g suggest a novel hydrogen-bonding between a relatively "nonacidic" bridging methylene proton and the carbonyl oxygen of the "internal" ester group at C8. X-ray crystallographic data indicate an unexpectedly small inclination angle of the two aromatic rings in 3g which would minimize the steric interaction between the syn ester group at C8 and H17. The [22]cyclophane 4g was found to adopt the anti conformation both in solid state and in solution. Results from the 1H NMR spectroscopic study of 4g show that the methoxy protons of the "internal" ester group at C7 are still located in the shielding zone of the opposite anti benzene ring. X-ray crystallographic data indicate an unexpectedly large inclination angle of the two aromatic rings in 4g which would minimize the steric interaction between the ester group at C7 and the opposite benzene ring. © 1994 American Chemical Society.
Source Title: Journal of Organic Chemistry
URI: http://scholarbank.nus.edu.sg/handle/10635/95049
ISSN: 00223263
Appears in Collections:Staff Publications

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