New syntheses of arylphosphonates.

The accompanying thesis begins with a review of the current methods of syntheses of carbocyclic and heterocyclic arylphosphonates. The new synthetic methods described all have one common feature; carbon-phosphorus bond formation is followed by formation of the aromatic nucleus. The condensation of vinamidinium salts with allylphosphonates is described. These condense, in the presence of a base, to give arylphosphonates. By use of a suitable vinamidinium salt and allylphosphonates, pyridylphosphonates were prepared. The reaction of a vinamidinium salt with a 2-dimethylhydrazono-alkylphosphonate is described; this reaction also produced a pyridylphosphonate. The reaction of enaminoketones with nucleophiles, such as hydrazine and its derivatives, is known to give five-membered heterocycles. The next study described is the reaction of a phospho-substituted enaminoketone with methylhydrazine, hydroxylamine, or amidines. Heteroarylphosphonates were synthesised. The synthesis of a phosphono-substituted enaminonitrile and a phosphono-substituted enaminoester, and their reactions with the above mentioned nucleophiles to give amino-or hydroxy-substituted heteroary Iphosphonates, is also described. A phosphono-substituted enamino-isonitrile did not give heteroaryIphosphonates. The condensation of enaminoketones with allyIphosphonate carbanions was then investigated. The reactions give good yields of arylphosphonates. Finally, some reactions of dienylphosphonates and some dienophiles are described. Again arylphosphonates were synthesised.