Phosphorus tribromide 9-phosphorylation

In view of the high price and other difficulties associated with the use of phosphoryl bromide, the transhalogenation of 2-chloro- and 2-chloro-4,6-dimethyl-pyrimidine (919) by treatment with inexpensive phosphorus tribromide to give their bromo analogues in >50% yield, assumes potential importance as a general method (67JCS(C)1204). 

Phosphorus tribromide and bromine 191 Phosphorylated deoxy sugar acids. . 88... 

Using Phosphorus Tribromide, Phosphorus Pentabromide, or Phosphoryl Bromide... 

He found that with ordinary commercial red phosphorus with 98 per cent, phosphorus, there dissolved 0-056 and 0-108 per cent, of phosphorus in respectively 10 and 42 hrs., and with a finely-divided sample 0-092 and 0-116 percent, phosphorus in 10 and 20 hrs. respectively. R. Schenck found that 100 grms. of phosphorus tribromide dissolved 0-2601 grm. of scarlet phosphorus at 172°, and 0-3634 grm. at 184°. E. Baudrimont showed that yellow phosphorus does not attack phosphoryl bromide at the b.p. L. Rosenstein found that soln. of arsenates, and arsenic, antimony, or bismuth salts are not reduced by boiling with red phosphorus but W. Finkelstein found that a nitrobenzene soln. of arsenic trichloride is reduced by yellow phosphorus and arsenic is deposited. 0. Ruff observed that phosphorus reacts with antimony trichloride in the presence of a little aluminium chloride. F. E. Brown and J. E. Snyder observed that vanadium oxytrichloride is without action on red or white phosphorus. 

A. Michaelis did not succeed in making pyrophosphoryl bromide, P203Br4, by the action of nitrogen peroxide or trioxide on phosphorus tribromide—the products are phosphorus pentoxide and phosphoryl bromide. T. E. Thorpe and A. E. H. Tutton said metaphosphoryl bromide, P02Br, is produced by the action of bromine on phosphorous oxide as indicated above, and it remains as a residue after the phosphoryl bromide has been removed by distillation. 

Nonmetal Halides. Vigorous or explosive reactions occur with phosphorus tribromide on addition of drops of water,20 phosphorus trichloride, phosphorus pentachloride,21 diselenium dichloride,22 sulfur dichloride, boron tribromide, sulfur dibromide,17 seleninyl bromide,23 phosphoryl chloride, sulfinyl fluoride, silicon tetrachloride, and silicon tetrafluoride.24... 

The classical route to chloropyrazines is by treatment of a hydroxy-pyrazine with phosphoryl chloride bromopyrazines are similarly prepared by using phosphoryl bromide, phosphorus tribromide, or a mixture of both. Thus, treatment of hydro xypyrazine with phosphoryl chloride gives chloropyrazine in 92% yield,147 and treatment of the hydroxy compound with a mixture of phosphoryl bromide and phosphorus tribromide gives bromopyrazine in 58% yield.266 The use of phosphorus pentahalides frequently leads to substitution products (Scheme 22) for example, when hydroxypyrazine is treated with a mixture of phosphoryl bromide and phosphorus pentabromide both monobromo- and 2,6-dibromopyrazines are formed.287,268 Bromina-tion of hydroxypyrazine with bromine in the presence of small... 

Many derivatives of carboxy chloropyrazines have been prepared by the action of phosphoryl chloride on the corresponding hydroxypyrazine. In this way were prepared 2-chloro-3-methoxycarbonylpyrazine (371, 423, 836), 2-chloro-3-methoxycarbonyl-5,6-diphenylpyrazine (but the corresponding hydroxy compound did not react with phosphorus tribromide) (837), and 3-chloro-2-methoxycarbonyl-... 

Hydroxypyrazine with phosphoryl bromide and phosphorus pentabromide has been found to give a mixture of 2-bromopyrazine and 2,6-dibromopyrazine (818, 865) the former was converted to the latter under similar reaction conditions (865). Phenyl-substituted 2-hydroxypyrazines were found to be transformed in good yield by phosphorus tribromide alone to the corresponding... 

Phosphonitrilic chloride, see Hexachloro-cyclotriphosphatriazene Phosphonium y tides, 168 Phosphoric acid, 230, 231 Phosphorous acid, 329 Phosphorus pentachloride, 63,120 Phosphorus pentoxide, 164 Phosphorus pentoxide-r-Amine, 329-330 Phosphorus tribromide, 330, 463 Phosphoryl chloride, 51, 63, 129, 187, 382 Phosphoryl chloride-Phosphoric acid-Phosphorus pentoxide, 331 Phosphoryl chloride-Pyridine, 330, 331 Phosphoryl chloride-Stannous chloride-Pyridine, 331... 

Phosphoryl bromide is a solid which is normally diluted with phosphorus tribromide, an inert solvent, or a tertiary amine for the exchange of a hydroxy group by a bromine substituent. Diazotization of pyrimidinamines in the presence of a large excess of bromide ions provides the corresponding bromides in low to moderate yields . 

The action of phosphorus halides on phenanthridones offers a convenient route to the corresponding 6-chloro- or bromophenanthri-dines, and further examples of this process have been reported since the last review. A mixture of phosphorus tribromide and bromine converts phenanthridone (in toluene) into 6-bromophenanthridine in fair yield.Phosphoryl chloride, alone or in the... 

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