Attack on Nitrogen, Chalcogen or Halogen

Kinetic data, activation parameters, and Hammett p values have been reported for the reaction of trico-ordinate phosphorus compounds with diphenyl trisulphide, and the results discussed in terms of a biphilic mechanism.A dithymidyl 3 -S phosphorothioate (33) has been prepared from a thymidin-3 -yl disulphide and a dimethyl 5 -thymidyl phosphite.  

Tervalent phosphorus acid esters, and triphenylphosphine, attack 2-bromothiazole (34) at bromine in alcoholic solvents to give thiazole and the oxidised phosphorus compounds. A similar attack of tris(diethylamino)phosphine on the bromine atom of bromopentafluorobenzene was used to prepare a series of main-group-four pentafluorophenyl derivatives, e.g. (35). A full paper has appeared on the fluoridation of trimethylsilyl phosphites, or phosphoramidites, with sulphury chloride fluoride. The mild conditions allowed the preparation of sensitive nucleoside derivatives, e.g. (36) and (37). 

3 Attack on Nitrogen, Chalcogen or Halogen. - Esterifications of racemic alcohols with acids have been realised with moderate enantiospecificity when 

Several new sulfur transfer reagents for the oxidation of oligonucleoside phosphites to phosphorothioates have been proposed this year. These include the disulfonyldisulfides (23), and the two cyclic disulfides (24) and (25).  

Tris(dimethylamino)phosphine with iodine in diethyl ether gave a solid which according to solid-state P NMR had the ionic structure (26) in contrast to most other phosphine-iodine addition compounds. AT-Chlorodiisopropylamine reacted with aminophosphines, e.g. (27), to give products of chlorine attack, e.g. 

Phosphites are fairly easily oxidised to thiophosphates with sulphur in pyridine/ 

Phosphorodiamidites, e.g. (48), and M-chloroamines (49) gave exclusively di-amidochloridates, e.g. (50), in methylene chloride, whereas in petroleum ether some amidate, e.g. (51), was formed as well. The reactions of carbon tetrachloride with alkylbis(dialkylamino)phosphines (52) have been further studied this year. The remarkable rearrangement (53) to (54) occurs only with large isopropyl substituents on nitrogen, and with alkyl or hydrogen on the ylidic carbon. 

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Attack on Nitrogen, Chalcogen, or Halogen.- Some tertiary alkyl azides and tris(dimethylamino)phosphine gave thermally stable phosphazides (24), allowing the X-ray crystal structure of one to be determined. ... 

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