Alternative Synthesis of A C,C-Diacetylenic Phosphaalkene

Abstract

Bis(trimethylsilyl)-terminated C,C-diacetylenic phosphaalkene was prepared from Mes*PCl₂ and a propargylic Grignard reagent that in turn was formed from 3-bromo-1,5-bis(trimethylsilyl)penta-1,4-diyne and Rieke-Mg.     

Toward Metathesis Reactions on Vinylphosphaalkenes

Abstract

Attempts to utilize C-ethylenic phosphaalkenes in metathesis reactions are discussed. Unprecedented reactivity is observed where the vinylphosphaalkene undergoes the first step of the catalytic cycle and cross-metathesis with the phenylmethylene moiety of Grubbs 2nd generation catalyst. However, homo-metathesis reaction to form 1,6-diphosphahexa-1,3,5-triene is not observed, presumably due to steric constraints.     

‘Phospha-variations’ on the themes of Staudinger and Wittig: phosphorus analogs of Wittig reagents

The Wittig and Aza-Wittig reactions have undergone tremendous development over the past 50 years in light of their potential in organic synthesis to construct carbon–carbon and carbon–nitrogen double bonds. In contrast, the development of the analogous phospha-Wittig reaction has only seen progress over the last 12 years. A phospha-Wittig process is one that uses phosphaylides to convert carbonyl compounds to new materials possessing phosphorus–carbon double bonds (phosphaalkenes). The phospha-Wittig reaction has evolved from initial work involving metal-assisted phospha-Wittig reactions to phospha-Wittig reactions, of terminal phosphinidene complexes to, more recently, free phosphanylidene-σ⁴-phosphoranes as phospha-Wittig reagents. The major developments in the phospha-Wittig reaction are highlighted and divided into these three methodologies. The complementary nature and the differences between the three approaches is also discussed. Finally, wherein applicable, comparisons between the Wittig reaction and the phospha-Wittig reaction are presented.     

Low-Coordinated Organophosphorus Compounds

Low-coordinate organophosphorus compounds can be prepared by steric protection. They are diphosphenes, phosphaethenes, phosphaallenes, phosphabutatrienes, phosphaalkynes, and so on, of coordination number 2 and 1 .