Aspects of organophosphorus chemistry

Chapter 1 This chapter is concerned with some reactions of diphenylvinylphosphine oxide (1). Phosphine oxfide (1) is known to undergo nucleophilic additions analogous to the Michael reaction. Triphenylvinylphosphonium bromide also undergoes a number of nucleophilic additions, including the Schweizer reaction. Thus, Triphenylvinylphosphonium bromide, upon treatment with the sodium salts of benzoin or salicylaldehyde, yields 2,3-diphenyl 2,5-dihydrofuran and 3,4-chromene, respectively. An attempt to extend the Schweizer reaction to phosphine oxide (1) was not not successful. Several possible synthetic routes to epoxyvinyldiphenylphosphine oxide (2) have been explored. Phosphine oxide (1) was found to be inert to several epoxidising conditions, for example, unbuffed trifluorperoxide/Triton B in methanol. Phosphine oxide (1) was converted to bis-(2-diphenylphosphinylethyl)peroxide (3) in 79% yield, by treatment with alkaline hydrogen peroxide. Peroxide (3) is usually stable. Reaction of (3) with lithium aluminium hydride gave 2-hydroxyethyl diphenylphosphine oxide (4) in 84% yield. Phosphine oxide (1) was converted to 1,2-bis-(diphenylphosphinyl)ethane (5) upon treatment with aqueous methanolic sodium hydroxide, in 96% yield. Phsophine oxide (5) had also previously been obtained by the reaction of triphenylvinylphosphonium bromide with sodium hydroxide. Phosphine oxide (5) was alos isolated in 19% yield from the treatment of phosphine oxide (4) with two mole equivalents of butyllithium, and subsequent treatment with bromine (Scheme 1). Scheme 1 On the basis of the spectroscopic properties of phosphine oxide (1), it is considered that there is little congugation between the C=C and hte P=O groups. [please see pdf for full abstract