Chemistry of phosphorus ylides 31: Reaction of azidocoumarin with active phosphonium ylides, synthesis and antitumour activities of chromenones

BPh3-Catalyzed [2+3] Cycloaddition of Ph3PCCO with Aldonitrones: Access to 5-Isoxazolidinones with Exocyclic Phosphonium Ylide Moieties

A method for the generation of 5-isoxazolidinones with exocyclic phosphonium ylide functionalities via [2+3] cycloaddition of Ph₃PCCO and aldonitrones has been developed and applied in the synthesis of 4-alkylidene-5-isoxazolidinones via Wittig olefination. The reaction proceeds by BPh₃ catalysis under mild conditions and with a broad substrate scope. A reaction pathway involving the activation of the aldonitrone via interactions with the Lewis acid BPh₃ is proposed.

Geminal Dianions Stabilized by Main Group Elements

This review is dedicated to the chemistry of stable and isolable species that bear two lone pairs at the same C center, i.e., geminal dianions, stabilized by main group elements. Three cases can thus be considered: the geminal-dilithio derivative, for which the two substituents at C are neutral, the yldiide derivatives, for which one substituent is neutral while the other is charged, and finally the geminal bisylides, for which the two substituents are positively charged. In this review, the syntheses and electronic structures of the geminal dianions are presented, followed by the studies dedicated to their reactivity toward organic substrates and finally to their coordination chemistry and applications.

Chemistry of Phosphorus Ylides: Part 44 Reaction of 1-Trimethylsilyl-1H-Imidazole with Phosphorus Reagents. A Convenient Synthesis of Phosphorus Silyl Imidazoles

The reaction of 1-trimethylsilyl-1 H-imidazole with nucleophilic active phosphacumulenes afforded imidazole silyl phosphoranylidenes or imidazole phosphoranylidenes according to the reaction conditions. The reaction of hexaphenylcarbodiphosphorane with 1-trimethylsilyl-1 H-imidazole resulted in the formation of silyl phosphoranylidene phosphoranyl imidazole, silyl phosphoranylidene imidazole and triphenylphosphane. Moreover, Lawesson and Japanese reagents afforded imidazole phosphinothioic thioanhydrides.

Chemistry of Phosphorus Ylides: Part 41 Synthesis of Antimicrobial Agents from the Reaction of Aminoantipyrine, Coumarin- and Quinoline-carbaldehyde with Phosphacumulene and Phosphaallene Ylides

Pyrrolo-pyrazoles were obtained from the reaction between phosphacumulenes and aminoantipyrine, while the reaction with the phosphaallene (hexaphenylcarbodiphosphorane ylide) afforded the azaphosphole and pyrazolo-phosphanylidene. The aminocoumarin carbaldehyde gave the chromeno-phosphanylidene and the chromeno-pyridinone, when it was allowed to react with phosphacumulenes. The reaction of chloroquinoline carbaldehyde with the phosphacumulenes, gave chloroquinoline phosphanylidenecyclobutane, while the reaction with phosphaallene resulted in the formation of oxaphosphetane, phosphanylidene ethenyl- and oxaphosphetyl-quinoline. The structure of cyclobutanedione was confirmed by X-ray crystallography. The antimicrobial activity of the new compounds is also reported.