PHOSPHORYL TO CARBONYL MIGRATION OF AMINO GROUPS IN MIXED ANHYDRIDES. REACTIVITY AND CRYSTAL STRUCTURE OF N-METHYL-2-BENZOYLOXY-2-OXO-1,3,2-OXAZAPHOSPHORINANE |
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| Authors: | J Symes T A Modro M L Niven |
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| Institution: | 1. Department of Chemistry , University of Pretoria , Pretoria, 0002, South Africa;2. Department of Physical Chemistry , University of Cape Town , Rondebosch, 7700, South Africa |
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| Abstract: | Abstract Cyclic mixed anhydride, N-methyl-2-benzoyloxy-2-oxo-1,3,2-oxazaphosphorinane (1a) has been synthesised and the rate of its fragmentation involving nitrogen migration from phosphorus to carbonyl carbon has been measured. (1a) was found to be ca. 60 times less reactive than the non-cyclic, O-methyl-N,N-dimethyl analogue. The crystal and molecular structure of (1a) has been determined using x-ray diffraction. Pna21, a=22.229(6), b=7.597(2), c=7.210(2) Å; V=1217.6(6) Å3. Final R=3.08% for 1037 reflections with I(rel) > 2sgrave]I(rel) and 157 parameters. The observed conformation of the molecule of (1a) is very different from that required for the fragmentation to occur; in order to achieve the geometry postulated for the transition state significant rotations about the Psbnd]O and Osbnd]C bonds would be necessary and steric hindrance by the 4,6-axial hydrogens would be expected. |
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| Keywords: | Conducting polymers oligomeric heteroarylenes UV spectra oxidation potentials |
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