Phosphine oxides vinylphosphine

A new enephosphinilation of ketones has been developed, based on the Shapiro decomposition of tri-sylhydrazones with BuLi followed by trapping with chlorodiphenylphosphine (Scheme 21). Oxidation of the resulting vinylphosphines with 30% hydrogen peroxide or 40% peroxyacetic acid/sodium carbonate yields the corresponding phosphine oxides. 

Pyrazoles (38) are formed in good yields by the dipolar addition of A -phenylsydnone to diphenyl(prop-l-ynyl)phosphine oxide at high temperatures. similar additions of diazodiphenylmethane to a series of vinylphosphine oxides result in the formation of 1-pyrazolines (39), which... 

A new synthesis of vinylphosphine oxides is available from the addition of secondary phosphine oxides to enol acetates to give (43), followed by thermolytic... 

Water-soluble phosphines, such as 3,3, 3"-phosphanetriyltris(benzenesul-fonic acid) (TPPTS) or m-monosulfonate, give quantitatively the water-soluble phosphonium salts when reacted with a,p-unsaturated acids in water (Larpent and Patin, 1988). They also react with activated alkynes, affording vinylphosphonium salts, vinylphosphine oxides or alkenes depending on the pH of the aqueous solution (Larpent et ai, 1990). 

A cross-couphng approach has been used to functionalize chiral cycloalkenyl substrates in order to prepare enantiopure chiral phosphine precursors (Scheme 4.279) [443]. The catalyst system used cesium carbonate as the base and afforded excellent yields of the vinylphosphine oxide after oxidation with hydrogen peroxide. No scrambling of the neighboring chiral centers was reported. 

SCHEME 4.280 Synthesis of a chiral phosphine from a vinylphosphine oxide [444]. 

The copper-promoted reaction between vinylzirconocenes and chlorophosphines generated vinylphosphines in moderate to excellent yields (Scheme 4.312 and 4.313) [478]. While this might seem like a cumbersome approach to the synthesis of vinylphosphines, the vinylzirconocene precursors were readily prepared from CpjZrHCl. Once generated, the vinylphosphines were protected from unwanted air oxidation through the formation of phosphine-boranes. Using this protocol, a host of vinylzirconocenes were readily... 

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