Aza-Wittig reaction of N-phosphorylalkyl phosphazenes with carbonyl compounds and phenylisocyanate.: Synthesis of 4-amino-3-phosphoryl-2-azadienes and pyrazine-phosphonates

Simple and functionalized N-phosphorylalkyl imines and N-phosphorylalkyl-N'-phenyl-carbodiimides are obtained by aza-Wittig reaction of phosphazenes derived from aminophosphonates with carbonyl compounds and phenyl isocyanate. The reaction with dimethylformamide diethyl acetal (DMF-DEA) of these functionalized imines leads to the synthesis of 4-amino-3-phosphoryl-2-azadienes. N-Phosphorylmethyl imine derived from benzaldehyde can be used for the preparation of substituted pyrrole-phosphonates, while acid treatment of 4-dimethylamino-3-diethylphosphoryl-1-phenyl-2-azadiene gives diethyl 5-diethylphosphorylpyrazin-2-ylphosphonate. (C) 2003 Elsevier Science Ltd. All rights reserved.