Phosphinates vinylphosphinates

Numerous other reactions can be used to access phosphaalkenes. For example, treating the primary phosphine Mes PH2 with CH2CI2 in the presence of KOH gives Mes P=CH2 [54]. In addition, interesting reactions of tantalum-or zirconium-phosphinidenes with aldehydes have afforded phosphaalkenes [55, 56]. The 1,3-hydrogen rearrangement of secondary vinylphosphines to phosphaalkenes has also been used to prepare phosphaalkenes [57,58]. 

By Addition ofP—H to Unsaturated Compounds. This route continues to be exploited for the synthesis of polydentate tertiary phosphine ligands. Thus base-catalysed addition of diphenylvinylphosphine to the secondary phosphine (25) affords (26).23 Neopentylpolytertiaryphosphines, e.g. (27), have been similarly prepared24 by addition of primary or secondary phosphines to vinylphosphines (or the related phosphine sulphides, followed by a desulphurization step). 

In ethanol/water mixtures addition of sodium mercaptoalkane sulfonates on vinyldiphenylphosphine proceeds smoothly at room temperature and yields a variety of tertiary phosphines such as 24. Interestingly, at the beginning of the reaction the ethanolic solution of the vinylphosphine and the aqueous solution of the educt comprise two separate phases and this is favourable for the high yields obtained (59-97%) [30]. 

Another equally successful method for the preparation of bisphosphinoethanes is the base-catalysed addition of a secondary phosphine to a vinylphosphine.40 The reaction (Scheme 19) itself seems very straightforward providing the starting materials are not too difficult to make. 

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. 

Several addition reactions of unsaturated phosphonic and phosphinic esters have been reported during the course of the year. Dithiophosphoric acids add to 2-alkoxy-vinylphosphine esters in the expected manner, and in the addition of phenyl azide to vinylphosphonates, the initial triazole (95) may be thermolysed to a C-phosphory-lated aziridine, but in the presence of triethylamine the final products are 2-anilino-vinylphosphonates. ... 

Methylated poly(tertiary)phosphines, e.g. (18), can be made by the base-catalysed addition of P—H to vinylphosphine sulphides. The protecting sulphur atom(s) are removed by treatment with lithium aluminium hydride. 

The synthesis of primary alkenylphosphines has been accomplished utilizing the same rDA method that was used to synthesize primary enamines. The synthesis of primary alkenylphosphines had been an unsolved problem owing to the high reactivity of the phosphine group under acidic, basic and neutral conditions. The preparation of vinylphosphine (38a) and isopropenylphosphine (38b) by FVP of the apprc riate anthracene (37) or 1,3-diphenylbenzofuran (39) adduct has been accomplished as shown in equation (26). ( )-Prop-l-enylphosphine was synthesized by a similar rDA route. These phosphines were found to be surprisingly stable, with a half-life of approximately 8 d for (38a). 

Preparation of Phosphines by Addition of P-H to Unsaturated Compounds. - The second part of a review of P-H addition to carbon-carbon multiple bonds has appeared.A range of heterogeneous catalysts has been developed for the addition of phosphine to alkenes. Radical-induced addition of bis(phenylphosphino)methane to vinylphosphines is the key step in the synthesis of the tetra(tertiary phosphines),(38) each of which exists in meso- and... 

Miscellaneous.—Polytertiary phosphines and phosphinoarsines have been prepared by the base-catalysed addition of phosphorus-hydrogen or arsenic-hydrogen bonds to vinylphosphines or ethynylphosphines. The same type of reaction was utilized to prepare the diphosphine (13). Radical addition of primary phosphines to vinylphosphines has also been... 

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... 

King et developed a route to poly(tertiary phosphines) by use of a base-catalyzed addition of a phosphorus-hydrogen bond to the carbon-carbon double bond of various vinylphosphine derivatives the first extensive series of methylated polyphosphines were prepared this way. The synthesis of unsymmetrical diphosphines of the type i 2PCH2CH2P(CH3)2 involves addition of a P-H bond to CH2=CHP(S)(CH3)2 via potassium tert-bwioxxdQ catalysis, followed by desulfurization with LiAlH4 in boiling dioxane (i.e.. Equations 10,11). 

Keiter s data suggest that the best results are obtained by building the polyphosphine from a vinylphosphine ligand bonded to the transition metal complex of interest. This approach should be limited only by the lability of the complex and the susceptibility of other attached ligands to reaction under the experimental conditions employed. It should also lead to syntheses of new cyclic and acyclic tri- and tetra-phosphines coordinated to the metal (or cluster) used for the template. 

Examples of electrophilic addition of secondary phosphines to alkenes or alkynes were described. [114, 124, 125, 135]. Glueck [124-126] reported enantioselective tandem reaction of alkylated/arylation of primary phosphines catalyzed by platinum complex, proceeding with formation of chiral phosphaace-naphthenes. Palladium-catalyzed hydrophosphination of alkynes 219 tmder kinetic resolution conditions gave access to 1,1-disubstituted vinylphosphine boranes 220. However, despite screening several chiral ligands, temperatures, and solvents, the... 

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