Synthesis and Pyrolytic and Kinetic Behaviour of β,δ′-Dioxo-Stabilised Phosphorus Ylides: Convenient Preparation of γ,δ-Alkynyl Ketones and 2,3-Functionalised Butadienes
✍ Scribed by R. Alan Aitken; Nouria A. Al-Awadi; Mark E. Balkovich; Hans Jürgen Bestmann; Oliver Clem; Scott Gibson; Andreas Groß; Ajith Kumar; Thomas Röder
- Book ID
- 102173629
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 140 KB
- Volume
- 2003
- Category
- Article
- ISSN
- 1434-193X
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Both ketone‐ and ester‐stabilised phosphorus ylides undergo Michael addition to vinyl ketones to give the β,δ′‐dioxo ylides 3 and 5, respectively, although in the latter case careful temperature control is required to avoid an undesired side‐reaction. Under conditions of flash vacuum pyrolysis at 650 °C the ylides 3 generally undergo Ph~3~PO extrusion to afford the γ,δ‐alkynyl ketones 14, although these are found to partly undergo a secondary fragmentation. In contrast, the ylides 5 react under the same conditions to give the synthetically useful 1,3‐dienes 20 by way of cyclobutenes. Rate constants for the reaction of selected ylides 3 and 5 are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)