Stereoisomerism in pentaerythritol-bridged cyclotriphosphazene tri-spiranes: spiro and ansa 1,3-propanediyldioxy disubstituted derivatives
Aylin, U. and Coles, Simon J. and Davies, David B. and Eaton, R.J. and Hursthouse, Michael B. and Kiliç, A. and Shaw, Robert A. (2005) Stereoisomerism in pentaerythritol-bridged cyclotriphosphazene tri-spiranes: spiro and ansa 1,3-propanediyldioxy disubstituted derivatives. European Journal of Inorganic Chemistry 2005 (6), pp. 1042-1047. ISSN 1434-1948.
Four isomeric products were isolated and purified from the reaction of 1,3-propanediol with the tetra-spirane cyclophosphazene-organophosphate compound (1): viz. the di-monospiro (2a), di-monoansa (2b) and two monospiro-monoansa derivatives (2c) and (2d). It is shown by 31P NMR spectroscopy on addition of a chiral solvating agent (CSA) that both the di-monospiro (2a) and di-monoansa (2b) derivatives are racemates, as expected, whereas no splitting of NMR signals occurred on addition of CSA to solutions of (2c) and (2d). It is found by X-ray crystallography that the two monospiro-monoansa spirane derivatives, (2c) and (2d), are meso diastereoisomers, which represent a new case of the stereochemistry of bis di-substituted cyclophosphazene derivatives of (1). It is also observed from the 31P NMR spectrum of the reaction mixture, supported by the yields of pure compounds, that formation of a spiro group is about 4.5 times more likely than that of an ansa moiety under the conditions of the reaction.
|Additional Information:||Available from http://www.interscience.wiley.com/|
|Keyword(s) / Subject(s):||cyclotriphosphazene derivatives, trispiranes, NMR spectroscopy, tetraspiranes, x-ray diffraction|
|School:||Birkbeck Schools and Departments > School of Science > Biological Sciences|
|Depositing User:||Sandra Plummer|
|Date Deposited:||07 Jun 2006|
|Last Modified:||17 Apr 2013 12:32|
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