Phosphine oxides dichlorophosphines

Phosphonic chlorides can be prepared analogously from dichlorophosphines, and phosphine oxides from monochlorophosphines.106... 

The iodo-phosphine (50) decomposes at temperatures above —50 °C to give the phosphorane (51).42 Phosphorus trichloride is oxidized by the sulphenyl chloride (52).48 Aryl- and alkyl-dichlorophosphines have been converted into the phosphor-... 

Two examples are reported here based on the reaction of Reformatsky reagents with phosphorus(III) electrophiles. In equations 67 and 68, a dichlorophosphine or a monochlorophosphine is reacted with 2 or 1 equivalents of la in the presence of zinc in refluxing benzene. Quenching of the crude unstable tertiary phosphine with H202 allows one to isolate phosphino oxides 116 and 117 in good yields, generally as stable solid compounds154. 

The McBride synthesis has been applied to the preparation of chiral phosphetane oxides by the reaction of optically active dichlorophosphines with 2,3,3-trimethyl-l-butene. Thus, myrtanyl-, bornyl-, and isopinocamphenyldichloro-phosphines afforded the corresponding phosphetane oxides having chirality localized on both the phosphorus substituent and the phosphorus center. In all cases, epimeric mixtures are obtained (Equation 22) <1997JOC297>. 

In principle, any phosphorus(III) compound possessing one (phosphonous acid derivative) or two (phosphinous acid derivative) P—C bonds may be oxidized to the corresponding derivative of the quinquevalent phosphonic or phosphinic acid. In practice, this might be difficult to achieve because of the extremely high reactivity of the phosphorus(III) compound in oxidation under both anhydrous or aqueous conditions, and it might also prove inconvenient because of difficulties in the synthesis of the phosphorus(III) compound. Alternative synthetic routes are always available. A phosphonous dichloride (dichlorophosphine) (317) may be converted into the phosphonic diester 319 by way of the phosphonous diester 318 alternatively, the original dichloride 317 may be first oxidized to the phosphonic dichloride 320 before esterification to 319 a similar sequence exists for the phosphinous-phosphinic series. 

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