Phosphorylation halide method

The new phosphorylation method was further applied to halides having N-benzyloxycarbonyl (Z) ( and >), N-acetyl ( ) and N-... 

The coupling of phosphoryl or phosphinyl amides with phosphoryl or phosphinyl halides is an excellent method for the preparation of unsymmetrical ligands, and affords the synthesis of compounds with both organic groups and chalcogens differing. 

By far the most frequently used method is the deprotonation with potassium tert-butoxide, which gives the potassium salts in nearly quantitative yields. The method seems to be usable for any bis(chalcogenophosphinyl and -phosphoryl)imide and has been employed for a broad diversity of derivatives, regardless of the nature of the chalcogen.2,26,30,33,36-38,49,89,91,99 If the salts are needed for further use in reactions with metal halides to form complexes, the potassium salt can be used in situ, without isolation, e.g., with zinc(II) chloride or palladium and platinum chloro complexes.41,43 Potassium metal in THF also forms the salt K[SPh2PNPPh2S] in 82% yield, 38 but the method is not practical for preparative purposes. Potassium-crown ether complexes, [K(18-crown-6)][Q1Ph2PNPPh2Q1] with Q1 = O,92 Q1 = S,93 and Q1 = Se,98 have been prepared by direct complexation of the potassium salt with the macrocyclic ligand. 

Because heteroatom-substituted vinylphosphonates such as enol phosphates and vinyl halides are masked acetylenic compounds, a variety of methods have been developed for their elaboration and subsequent use in the synthesis of dialkyl 1-alkynylphosphonates. These eliminations usually have the leaving group P to the phosphoryl group, although cases in which the leaving group is a to the phosphorus center are also known (Scheme 1.12). 

Phosphorylation of At2PH-BH3 with aryl halides proceeds under mild conditions using Pd-Cu catalyst and P-chiral phosphine-boranes of high enantiopurity are prepared by this method. As an effective ligand, MePPh2 is used with Pd(OAc)2. The phosphine-borane 50 was prepared in 68 % yield by phosphorylation of optically active (Sp)-methylphenylphosphine-borane (47) via 48 with the iodide 49 in the presence of the Pd(OAc)2-MePPh2 catalyst and Cul as a cocatalyst at 0°C for 3 days. The reaction proceeded with retention of stereochemistry and the asymmetrically substituted phosphine 51 with 99% ee was obtained [15]. 

An important preparative method is the reaction of alkylmagnesium halides with phosphoryl, phosphonyl or phosphinyl halides (6.112-6.114). 

Allyl bromide added drop wise with stirring to a soln. of tetramethylammonium di-tert-butyl phosphate in boiling dimethoxyethane, refluxed 3 hrs., the crude intermediate triester dissolved in benzene and trifluoroacetic acid, allowed to stand 18 hrs. at room temp. allyl phosphate. Y 83% as the anilinium salt. -This method appears to be particularly suited to the phosphorylation of polyfunctional halides containing no acid-labile groups. F. e. s. A. Zwierzak and M. Kluba, Tetrahedron 27, 3163 (1971). 

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