Triphenyl phosphite dibromide

In addition to the sulfonyloxy displacement reaction which may occur on halogenation with triphenyl phosphite complexes, the possibility of acetal migration (with appropriate structure) should not be overlooked. Thus, 1,2 5,6-di-O-isopropylidene-a-D-glucofuranose with triphenyl phosphite dibromide in benzene for 48 hours afforded " (presumably) 6-bromo-6-deoxy-l,2 3,5-di-O-isopropylidene-a-D-glucofiiranose, which was hydrolyzed to 6-bromo-6-deoxy-D-glucose in 10% overall yield. In some compounds, steric factors may prevent the introduction of halogen. With vicinal glycols and triphenyl phosphite methiodide, phosphonic ester formation occurs instead of halide production, but this reaction may be eliminated by use of triphenylphosphine in carbon tetrachloride. 

Among the synthetic contributions this year, it is appropriate to discuss first the synthesis of ( + )-dubinidine (11), since the structure of this alkaloid had been in doubt for some time. The synthesis was accomplished by treating ( )-platydesmine (9 R = H) with triphenyl phosphite dibromide and potassium... 

Phosphonitrile chloride Chlorophosphoranes (C,H,),PF2, (C,H,),-PCI2, (C,H,),PBr2 R2PCI, (C,H,)2PF, Triphenyl phosphite dibromide Triphenyl phosphite methiodide... 

Triphenyl phosphite dibromide Triphenyl phosphite methiodide F2I4... 

Triphenyl phosphite dibromide/pyridine Replacement of hydroxyl by bromine... 

An equimolar mixture of 3,4-pentadien-l-ol and pyridine allowed to react with triphenyl phosphite dibromide l-bromo-3,4-pentadiene. Y 76-80%.—Similarly Propargyl alcohol propargyl bromide. Y 72-77%. F. e. s. D. K. Black et al., Tetrah. Let. 1963, 483. 

Phosphite diiodide converts alcohols to iodides. This reagent has been used much less often than the corresponding dibromides or dichlorides. Phosphite methiodides give better yields of iodides in the reaction with primary, secondary and tertiary alcohols and are simple to use. Neopentyl iodide is isolated in 70% yield from the reaction of triphenyl phosphite, neopentyl alcohol and methyl iodide (equation 25). This reaction is remarkable considering the severe steric bulk of the neopentyl group which often makes rearrangement become the major process. 

Potassium permanganate. Dimethyl sulfide-Chlorine. Dimethyl sulfoxide. Dimethyl sulfoxide-Chlorine. Dimethylsulf-oxide Sulfur trioxide. Dipyridine chro-mium(VI) oxide. Iodine. Iodine-Potassium iodide. Iodine tris(trifluoroacetate). Iodosobenzene diacetate. Isoamyl nitrite. Lead tetraacetate. Manganese dioxide. Mercuric acetate. Mercuric oxide. Osmium tetroxide—Potassium chlorate. Ozone. Periodic acid. Pertrifluoroacetic acid. Potassium ferrate. Potassium ferricyanide. Potassium nitrosodisulfonate. Ruthenium tetroxide. Selenium dioxide. Silver carbonate. Silver carbonate-Celite. Silver nitrate. Silver oxide. Silver(II) oxide. Sodium hypochlorite. Sulfur trioxide. Thalli-um(III) nitrate. Thallium sulfate. Thalli-um(III) trifluoroacetate. Triphenyl phosphite ozonide. Triphenylphosphine dibromide. Trityl fluoroborate. 

Related Reagents. A number of related reagents have been used for the conversion of alcohols to bromides. Other reagents for this purpose covered in this encyclopedia include l,2-Bis(diphenylphosphino)ethane Tetrabro-mide, Bromine-Triphenyl Phosphite, Hydrogen Bromide, Triphenylphosphine-Carbon Tetrabromide, and Triphenylphos-phine Dibromide. ... 

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