Hydroxyalkylphosphonium salts

In the case of phosphonium salts, some examples of decomposition by Hofmann elimination reactions are known. The phosphonium salts which normally undergo such a decomposition possess an activated hydrogen / to the phosphorus the salts 70, with a strong electron-withdrawing Z group on the carbon / to the phosphorus (reaction 202) and the a-hydroxyalkylphosphonium salts 71 (reaction 203)... 

N-acylaziridines occurs on treatment with triphenylphosphine with the formation of the ylides (67), thereby providing a route to a-substituted primary allylic amines via their in situ reactions with aldehydes.The reactions of triphenylphosphine with epoxides in phenolic media provide a new access to the vinyl-phosphonium salts (68). A route to 1-hydroxyalkylphosphonium salts is provided by the reactions of trimethyl- or triethyl-phosphine with aldehydes or ketones in the presence of anhydrous acids. The related 1-trimethylsiloxyalkylphosphonium salts can be isolated in the presence of trimethylsilyl chloride.Further Wittig-products have been isolated from the reaction of 1,2,3-indanetrione with triphenylphosphine, and, in related work, it has been shown that furoin is deoxygenated on heating with triphenylphosphine to form 2-furfuryl(2-furyl)ketone and triphenylphosphine oxide.The structure of the blue product from the reaction of triphenylphosphine with 2,3,5,6-tetracyano-7-oxabicyclo(2,2,1]hepta-2,5-diene has now been shown by X-ray techniques to be the stable ylide (69). ... 

Synthesis and reactions of oxaphospholanes using hydroxyalkylphosphonium salts 00YGK548. 

A general synthesis of 2-, 3-, and 4-hydroxyalkylphosphonium salts (137) is provided by the reactions of triphenylphosphine with cyclic ethers in the presence of strong acids.Dialkyldiphenyl-... 

Preparation.—Conventional quaternization reactions of phosphines with alkyl halides have been used for the preparation of chiral P-hydroxyalkylphosphonium salts for use in prostaglandin synthesis and of the salts (111), (112), and (113). This approach has also been used for the preparation of polymer-bound phosphonium salts for use in subsequent Wittig reactions and of a range of co-dialkylaminoalkylphosphonium salts. The salt (114), of limited thermal stability, is formed on treatment of the parent phenylphosphaferrocenophane (67, R = Ph) with iodomethane. The oxonium salt (115) is converted into the mixed onium salt (116) on treatment with triphenylphosphine. A range of... 

The reaction of a-branched aliphatic aldehydes with PH3 in hydrochloric acid does not yield hydroxyalkylphosphonium salts because of steric repulsion among the substituent groups. Instead, secondary phosphanes are obtained, in which phosphorus is part of heterocyclic 1,3-dioxa-5-phospha-cyclohexanes [134, 136 to 138, 179, 180]. 

Finally, a-acyloxyalkylphosphonium salts can be prepared in a classical way either by the esterification of an a-hydroxyalkylphosphonium salt306 or by alkylation of a tertiary phosphine by an a-chloroester306 however, the easiest way is by acylation of the adduct obtained in the reaction of a tertiary phosphine with an aldehyde (reaction 59)306,307 Further, this method of trapping allows a-silyloxyalkylphosphonium salts to be obtained121. 

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