Phosphine oxides alkynylphosphine

The aUcynylation of secondary phosphine oxides nsing iodonium salts is an effective ronte to the synthesis of alkynylphosphine oxides (Scheme 4.360) [541]. The chemistry was operationally trivial, and good to excellent yields of the alkynylphosphine oxides were... 

A practical method for the synthesis of axially chiral biaryl monophosphine oxides was developed by Tanaka and coworkers [104]. Enantioselective [24-24-2] cycloaddition of 1-alkynylphosphine 2-naphthol derivatives 2.157 with 1,6-diyne 2.156 in the presence of cationic rhodium catalyst including (R)-H8-binap (i.e., (R)-(4-)-2,2 -bis(diphenylphosphino)-5,5, 6,6, 7,7, 8,8 -octahydro-l,l -binaphthyl) leads to axially chiral phosphine oxides 2.158 in high yields and high enantioselectivity (Scheme 2.54)... 

Keywords Copper acetylides, secondary phosphine-boranes, 1,10-phenanthroline, oxygen atmosphere, toluene, room temperature, oxidative P-alkynylation, enantioselective alkynylphosphine-boranes... 

The syntheses of axially chiral biarylphosphine oxides based on alkynylphosphine oxide 2.157 and acetylene was carried out using chiral cobalt catalyst 2.159 [100, 105, 106]. The [24-24-2] cycloaddition, however, resulted in axially chiral biarylphosphine oxides 2.160 with moderate yield and enantioselectivity (Scheme 2.55). It was accompanied by a recovery of some of the corresponding phosphines. The newly obtained phosphines were used in the reaction of palladium-catalyzed hydrosilylation of unsymmetrical alkenes [100]. 

The catalyst-free and catalyzed addition of >P(0)H species to allenyl-and alkynylphosphine oxide was investigated. The reaction of diphenyl-allenylphosphine oxide with Ph2P(X)H was performed without solvent and catalyst. In this case, the major product was the a-methylene-ethylene(bis-phosphine) derivative, while the methyl-vinyl(bisphosphine derivative) was... 

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