Phosphoryl sulphoxides

Oxidation of phenyl hexyl sulphide with sodium metaperiodate gave also only a trace amount of the corresponding sulphoxide72. On the other hand, Hall and coworkers73 prepared benzylpenicillin and phenoxymethyl penicillin sulphoxides from the corresponding benzyl esters by oxidation with sodium metaperiodate in dioxane solution with a phosphate buffer. A general procedure for the synthesis of penicillin sulphoxides was reported later by Essery and coworkers74 which consists in the direct oxidation of penicillins or their salts with sodium metaperiodate in aqueous solution at pH 6.5-7.0. 1-Butadienyl phenyl sulphoxide 4475 and a-phosphoryl sulphoxides 4576 were also prepared by the same procedure. 

TABLE 24. Synthesis of vinyl sulphoxides 443 from a-phosphoryl sulphoxides 442... 

Sulphoxides can be used as phase transfer catalysts, for example, a-phosphoryl sulphoxides (Scheme 24) have been used as phase transfer catalysts in the two-phase alkylation of phenylacetonitrile or phenylacetone with alkyl halides and aqueous sodium hydroxide. However, they are considered to be inefficient catalysts for simple displacement reactions226. 

Phosphorylation 341, 342 Phosphoryl sulphoxides reactions of 333, 825 synthesis of 70, 246, 341, 342 Photochemical oxidation 877, 878 Photoelectron spectroscopy, of... 

The Horner-Wittig reaction of a-phosphoryl sulphoxides 442, which are chemically stable, results in the formation of a, -unsaturated sulphoxides 443 in high yields (equation 264). The reaction has been found to be non-stereoselective, mixtures of E and Z isomers being formed from aldehydes and unsymmetrical ketones . In the case of aromatic aldehydes this reaction can also be advantageously performed in a two-phase catalytic system even without the usual PTC catalysts (Table 24). Intramolecular Horner-Wittig reaction of a-phosphoryl-5-oxosulphoxides 444 leads to a, -unsaturated cyclic sulphoxides 445 (equation 265). Starting from optically active 0,0-... 

Chlorodiphenylphosphine 488 reacts with a-sulphinyl carbanions to give a-sulphinylphosphines 489 which undergo ready isomerization to a-sulphenylphosphine oxides 4W (equation 295). The report of Almog and Weissman that a-sulphinyl carbanions react with phosphorochloridates 491 to give a-phosphoryl sulphoxides 492 calls for correction (equation 296). Actually, the phosphorylation occurs at the oxygen atom of the ambident dimsyl anion, and is followed by the Pummerer-type reaction affording diethylphosphoric acid and tetraethyl pyrophosphate among other products . ... 

The reactions of phosphorylated carbanions have been extended to include those with sulphinate esters as a route to phosphoryl sulphoxides . The interaction of dimethyl... 

An interesting finding in this area is that no added catalyst is necessary in the reactions of equation (4). The assumption made was that phosphonate systems could, like their phosphonium ion counterparts, act as their own phase-transfer catalysts, and this is borne out by the use of a-phosphoryl sulphoxides and sulphones (13) and related compounds as the mediators of some two-phase car-banion alkylations. 

A. Nucleophilic Reactions of the P=0 Group.—Tris(trifluoromethyl)-phosphine oxide (33) reacts with hexamethyldisiloxane to give a phos-phorane, whose n.m.r. spectrum at — 140 °C shows non-equivalent trifluoromethyl groups. Although this unusual reaction clearly involves nucleophilic attack of the phosphoryl oxygen on silicon at some stage of the reaction, a full study of the mechanism has not been published. Tertiary phosphine oxides can be converted cleanly into dichlorophos-phoranes (34) by treatment with two moles of phosphorus pentachloride. Alkylation of the sodium salt of tetraphenylmethylenediphosphine dioxide (35) with alkyl halides, in dimethyl sulphoxide, has been reported to... 

The sulphoxide derivative (69) cannot be obtained by phosphorylation of the sulphoxide but has been prepared from the corresponding sulphide by oxidation with periodic acid. ... 

Chromans. - 2,4-Diethoxychromans (78) (mainly cis) represent a new type of chroman and have been prepared in high yield from a phenol (but not a deactivated phenol) and malonaldehyde bis(diethyl acetal) in the presence of SnCU they are converted into the benzopyrylium salts (79), in excellent yield, by treatment with perchloric acid. A Wittig-Horner reaction of the chiral phosphoryl ( S)-sulphoxide (81) and the ketone (80) gave the chiral sulphoxide (82), which was cyclized by aqueous alkali to a mixture which contained 22% diastereoisomeric excess of (25 )-chroman (i )-sulphoxide. This was converted, in three steps, into the aldehyde (83), which is a useful synthon for a-tocopherol. ... 

The reactions of tertiary phosphines are frequently driven by formation of the thermo-dynamically-stable phosphoryl (P=0) bond. Deoxygenation reactions are common in phosphine chemistry many oxygen-containing compounds, for instance diacyl peroxides, peresters, alkyl hydroperoxides, ozonides, amine oxides and sulphoxides, react with phosphines ... 

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