1.3- Dienylphosphine oxides

Exocyclic 1,3-dienylphosphine oxides can also be obtained by [Cp Ru (CH3CN)3]PF6-catalyzed hydrophosphinylative cyclization of 1,6-diynes via a H-atom transfer on the ruthenacyclopentatriene and subsequent intramolecular... 

In a ruthenium-catalyzed reaction with diphenylphosphine oxide, 1,6-diynes underwent a stereoselective and hydrophosphinylative cyclization to afford 1,3-dienylphosphine oxides (Scheme 50). ... 

A rationalization for the formation of 10 is presented in Scheme 4. The crucial feature is that lithiation of the oxide 7 occurs at two different sites, in both of which internal coordination to lithium is important. When lithiation occurs on the 6-carbon, giving 13, formation of the dienylphosphine oxide 11 results, and hence anion 12 arises. Upon quenching with water the dimeric dioxide 10 is formed. In a separate experiment, addition of benzaldehyde led to isolation of a trienylphosphine oxide whose formation we take to be further evidence for the anion 12. 0... 

Enynylphosphine oxides were prepared and then subjected to carbocu-pration reactions to give dienylphosphine oxides, as shown in Scheme 29 Arylhydrazono-alkylphosphine oxides were converted to the corresponding azoalkene derivatives on treatment with iodic acid (Scheme 30). Otherwise unreactive chloroarylphosphine oxides have been shown to undergo Suzuki coupling on MW irradiation in the presence of a highly active palladium-catalyst (Scheme 31 Treatment of 2-fluoro-5-nitrobenzyl bromide with active methylene compounds, such as a p-keto phosphine oxide under suitable conditions led to 4/7-1-benzopyrans (Scheme 32)." ... 

Since the successful use of dienylphosphine dichloride 2 [11], hexachloro-cyclotriphosphatriazene 3 [12], triphenylphosphine 4 [13] and diphenylchloro-phosphate 5 [14] in the synthesK of polyesters, Ogata et al. studied direct polycondensation of diacid and diamir in the presence of triphenylphosphine dichloride (TPPCI2) [15b] which can form in situ when triphenylphosphine is treated with hexachloroethane or when triphenylphosphine oxide interacts with phosgene or oxalyl chloride (Scheme 3) [15a]. 

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