Secondary phosphites vinyl

SCHEME 4.334 Copper-catalyzed coupling of secondary phosphites with vinyl bromides [497]. 

The copper-catalyzed cross-coupling of vinyl bromides with secondary phosphites has been reported (Scheme 4.334) [497]. Copper iodide was an effective catalyst for this reaction however, three equivalents of Cul were needed for each vinyl bromide. The authors were pleased to find that the stereochemistry of the vinylphosphonate mirrored the starting vinyl bromide. Although HMPA was a superior solvent for the reaction chemistry, the authors successfully used other solvents snch as DMF and tetramethylurea due to the potential carcinogenicity of HMPA. The overall reaction was carried out in two stages with the phosphonate anion generated in the first step, while the cross-coupling reaction was carried out in the second step. 

The products formed by hydrolysis are effective primary and secondary antioxidants. Polyfunctional antioxidants are formed during the application of cyclic arylene phosphites and various HD and chain breaking moieties which autosynergetically enhance their antioxidative activity. In addition to decomposing hydroperoxides, aromatic phosphites can also react with unsaturated (vinyl) groups in the polymer, coordinate with transition metal residues, help to preserve the hindered phenol, and prevent discoloration by reacting with quinoidal compounds. 

Phospha-Michael reactions are useful to establish a P-C bond. The addition of >P(0)H species (e.g., dialkyl phosphites and secondary phosphine oxides) at the end of electron-poor double bonds may be facilitated by bases, like NaOR, NaOH, or DBU [56]. The addition of P-heterocyclic nucleophiles was also studied. Dibenzo[c.e][l,2]oxa-phosphorine oxide (36) added easily on the double bond of methyl vinyl ketone xmder MW conditions in the absence of any solvent (Scheme 12) [57]. 

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