Synthesis of Amino Acid Derived Cyclic Phosphorus Ylides |
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Authors: | R. Alan Aitken Nazira Karodia Tracy Massil Robert J. Young |
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Affiliation: | 1. School of Chemistry, University of St. Andrews , St. Andrews, Fife , KY16 9ST , U.K.;2. Glaxo-Wellcome, Medicines Research Centre , Stevenage , SG1 2NY , U.K. |
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Abstract: | Abstract We recently reported the thermal elimination of Ph3PO from suitably protected aminoacyl ylides 1 as a route to acetylenic amino acid analogues 2. Pyrolysis of ylides such as 3 with a free amino group takes a different course. Ethanol is eliminated to give the c h i d cyclic ylides 4 which can be viewed as 3-triphenylphosphoranylidene tetramic acids. Specific examples prepared include 4 (R = Me, Pri), the parent compound 5 (from glycine) and the six-membered ring compound 6 (from p-alanine). Using a similar approach, bicyclic ylides such as 7 (from proline) can be prepared. In the case of the glutamate derived ylide 8, thermolysis initially gives a mixturc of 9 and 10 but these both cyclise to the bicyclic product 11 with time. The structure and reactivity of these interesting cyclic ylides are now being examined. |
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