Phosphine dimethyl, sodium salt

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... 

Preliminary bioassay showed that substitutent 2,6-Cl2 as Yj, on the phenoxy-benzene ring was beneficial to the inhibitory activity of the IIIH. For example, sodium salt of phosphinic acid HIH-IO (Yn=2,6-Cl2, R =pyrid-2-yl) displayed >90 % inhibitory activity against tested plant at 10 mg/L. However 2,6-Cl2 as Yj, was not so beneficial to the herbicidal activity of it corresponding (9, (9-dimethyl l-(pyrid-2-yl)methylphosphonate IJ-I4 and (9-methyl l-(pyrid-2-yl)methylphosphinate HIG-8. IIIH need to be further tested at a lower rate to make sure of their herbicidal activity and potential usage. Their inhibition against plant PDHc El will be studied. 

Allylic substitutions catalysed by palladium NHC complexes have been studied and the activity and selectivity of the catalysts compared to analogous Pd phosphine complexes. A simple catalytic system involves the generation of a Pd(NHC) catalyst in situ in THF, from Pdj(dba)j, imidazolium salt and Cs COj. This system showed very good activities for the substitution of the allylic acetates by the soft nucleophilic sodium dimethyl malonate (2.5 mol% Pdj(dba)3, 5 mol% IPr HCl, 0.1 equiv. C (CO ), THF, 50°C) (Scheme 2.22). Generation of the malonate nncleophile can also be carried out in situ from the dimethyhnalonate pro-nucleo-phile, in which case excess (2.1 equivalents) of Cs COj was used. The nature of the catalytic species, especially the number of IPr ligands on the metal is not clear. 

According to the literature [1], phosphonate or phosphinate salts could be generally synthesized by the reaction of the corresponding phosphonate or phosphinate esters with inorganic alkalis or salts. For example, as shown in Scheme 3.6, Baillie reported that sodium (9-methyl acetylphosphonate 1-1 could be obtained by demethylation of (9, (9-dimethyl acetylphosphonate 1-la with sodium iodide in butanone [1,5]. The phosphinate 2a could be hydrolyzed to give the corresponding salts 2 in 2 M sodium hydroxide aqueous solution [1]. 

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