Phosphoramidic dichloride

Reaction of the (S)-amino alcohol 171 with A-(2-bromoethyl)phosphoramidic dichloride or aryl phosphonodichloridates 154 in the presence of triethylamine led to the formation of a single diastereomer in each case of 1,3,2 oxazaphospholidine-2-ones 172a-e (taking into consideration that in the 31P-NMR spectra only one singlet in the range 6.49-2.45 ppm was observed) (Scheme 48) [79],... 

It was possible, however, to obtain a small yield of the expected phosphine oxide (isolated as the phosphinic acid) by converting di-o-tolylamine to the corresponding phosphoramidous dichloride, (o-MeC Ity NPC, dehydrohalogenating the latter substance, and treating the reaction mixture with water. 

Steric factors probably play a key role in determining the regiospecificity of the reactions leading to the phosphine oxides 4a and 4b. An intermediate involved in both cases is probably of type 5, in which ring closure preferentially occurs para rather than ortho to the bulky CF3 group. The preferential formation of 5b from the corresponding phosphoramidous dichloride is undoubtedly associated with the fact that... 

PHENYL-l-PENTANOL, 61, 42 (+)-(/ )-l-PHENYI -1-PENTANOL, 61, 42 (S)-1-PHENYL-l-PENTANOL, 61, 42 N-Phenylpyrrolidinone, 60, 68 Phosphoramidic dichloride, dimethyl- [677-... 

Lithium bis(trimethylsilyl)amide (2.50 mmol, 1.0 M in THF) was added dropwise to a solution of l,4-dimethoxy-2-hydroxymethylnaphthalene (2.29mmol) dissolved in 10 ml THF at —78°C. This was then added dropwise to a solution of bis(2-chloroethyl)phosphoramidic dichloride (2.75 mmol) dissolved in 20 ml THF, the reaction mixture stirred at —78°C 90 minutes, warmed to —20°C, and ammonia passed through the mixture 10 minutes. Thereafter, the mixture stirred an additional 10 minutes, 30 ml 2% HCl added, and then extracted 4 times with EtOAc. The combined organic layers were washed twice with saturated brine, dried, filtered, and evaporated. The mixture was purified by chromatography using methyl alcohol/EtOAc, 2 98, and the product isolated in 50% yield as a yellow oil, Rf = 0.59. H- and P-NMR data supplied. 

Bromoethyl derivatives were prepared using bis(2-bromoethyl)-phosphoramidic dichloride and its preparation is provided by the author. 

It is prepared by the interaction of bis-(2-chloroethyl) phosphoramide dichloride with propanolamine. 

When treated with four molar equivalents of a primary amine RNH2. the phosphoramidic dichloride (184) yields the triamide (185). When these (R = Me or Bn) are further treated with NaH, the sole products are the A/-phosphorylated aziridines (186), but for (185 R = aryl), a mixture of (186) and the cyclic triamide (187) results. 

Chlorination of aminopyrimidines, followed by treatment of the resulting phosphoramidic dichloride with ammonia, can lead either to the breakage of the N—P linkage [558] or to the formation of phosphoric triamides [559]. 

Phosphoramidic dichlorides react readily with alcohols, ammonia and primary amines to give phosphoramidates or phosphoryl amides (7.116). 

Phosphazenes of type (RO)3P=N CO R are much more resistant to alkaline hydrolysis than those of type R3 =N CO R or CljP NR. A -acyl trichlorophosphinimides and V-snlphonyl trichlorophosphinimides (Figure 7.16) readily hydrolyse, initially to phosphoramidic dichlorides (7.473) and (7.474). 

Thioesters, Selenoesters, and Thioamides.—Commercially available phenyl dichlorophosphate has been reported to be a superior reagent to MV-dimethyl-phosphoramidic dichloride (4, 244) for the preparation of thioesters directly from carboxylic acids and thiols. Carboxylic acid chlorides can be efficiently converted into thioesters by reaction with adducts formed between thiols and l-methylpyridine-3,5-dicarboxylates. Alternatively, copper(i) mercaptides, formed from thiols and CuaO, or thallous thiophenoxide can be used. The latter method can also be used to prepare selenoesters as well as a-phenylthio-and a-phenylseleno-acids and esters from a-halo-acids and a-halo-esters, respectively. 

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