Flash-Vacuum Pyrolysis of Stabilised Phosphorus Ylides, 9. Preparation and pyrolysis of β,γ-dioxo ylides, β,β′,γ,γ′-Tetraoxo Ylides and Hexaoxo Bis(ylides)

✍ Scribed by Aitken, R. Alan ;Karodia, Nazira

• Book ID: 102901242
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 554 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719970423

✦ Synopsis

Abstract

Six examples of the β,β′,γ,γ′‐tetraoxo phosphorus ylides 6 have been prepared. While they are found, upon flash‐vacuum pyrolysis (FVP) at 500°C to decompose to give no useful products, conventional pyrolysis by distillation at 200°C gives the trioxo alkynes 12 and 13 where R^1^ and R^2^ are alkoxy groups. Three examples of the previously unknown hexaoxo bis(ylides) 7 have been obtained but, with eight contiguous C=X functions, these are too fragile to give any useful product upon FVP. The pyrolysis of the simpler β,γ‐dioxo ylides 9 used to prepare 6 and 7 has also been examined for the first time and at 600°C it gives the alkynes 11 in low yield for R^1^ = OMe or OEt but not Ph. The fully assigned ^13^C‐NMR spectra of all the ylides 6, 7, and 9 are presented.