Reactions of Azovinylphosphonates with Nucleophilic Alkenes and Heterocycles: Synthesis of Tetrahydropyridazine-3-phosphonate and 2-Substituted-1-hydrazonoethylphosphonate Derivatives

Abstract

Transient azovinylphosphonates, generated in situ by base induced dehydrohalogenation of the corresponding 2-bromo- and 2-chloro-acetylphosphonate- tertbutoxycarbonyl hydrazones are intercepted by electron rich alkenes and heterocycles in hetero Diels-Alder reactions, producing tetrahydopyridazine-3-phosphonates or open chain α-hydrazono phosphonates.

Keywords:

• α-hydrazonophosphonates
• 3-phosphono-1,2-diaza-1,3-butadienes
• azovinylphosphonates
• addition-elimination
• cycloaddition
• tetrahydropyridazine-3-phosphonates

Acknowledgments

Thanks are due to Dr. T. L. Gilchrist for helpful discussions and Fundação Ciência e Tecnologia, UID 272/94, for financial support.