Isocyanates, reaction with phosphorus pentachloride

Alcohols add to this isocyanate in the expected way and the products were converted to iminophosphazenes by reaction with phosphorus pentachloride ... 

Salts are produced by the reaction of fluorophosphoranes with A -silylimines (94). Vinyl isocyanate reacts with phosphorus penta-chloride to give a hexachlorophosphate salt (95), which yields the phosphonic dichloride (96) on hydrolysis and distillation. Butyl cyanate reacts with phosphorus pentachloride to give two products, (97) and (98). ... 

The reaction of isocyanates with phosphorus pentachloride, and the reaction of secondary carbamoyl chlorides with chlorine, yield carbonimidoyl dichlorides. Gumpert in 1885 investigated the reaction of phenyl... 

A recent patent describes the formation of carbonimidoyl dichlorides in the reaction of several aliphatic and aromatic isocyanates with phosphorus pentachloride. This reaction can be conducted using phosphorus oxychloride as solvent, or without a solvent however, only from aliphatic isocyanates diisocyanates are good yields of... 

In the reaction of benzoyl isocyanate with phosphorus pentachloride reaction occurs exclusively on the C=0 group attached to the isocyanate moiety, and the chloroimidoyl-N-carbonyl chloride XXV is obtained in good yield ( ). 

In contrast, phosphoryl isocyanates are attacked by phosphorus pentachloride on the isocyanato group, with concomitant cleavage of the alkoxy groups by the generated hydrogen chloride. Thus, dichlorophos-phorylcarbonimidoyl dichloride (XXVIII) is obtained in the reaction of the phosphoryl isocyanate and phosphorus pentachloride ( " ). 

The reverse of this reaction is feasible in the aliphatic series, i.e. carbonimidoyl dichlorides can be obtained from isocyanates and phosphorus pentachloride, and subsequent reaction of the carbonimidoyl dichloride with a variety of sulfur compounds produces isothiocyanates. 

By analogy with the general synthesis of imidoyl chlorides it can be expected that carbamates and thiocarbamates undergo reaction with a variety of acid halides to afford 1-haloformimidates and 1-halothio-formimidates, respectively. For example, carbamates have been reacted with carbonyl chloride ( ), pyrocatecholphosphorus trichloride ( ), and phosphorus pentachloride ( ), and isocyanates were obtained. In view of the catalytic effect of N,N-dimethylformamide in the phosgenation of carbamates to isocyanates, the intermediacy of 1-chloroformimidates X is anticipated ( ). 

Acidic reagents seem to offer milder conditions. Dehydration reactions forming cyanides can be performed with phosgene [1049-1052], diphosgene [1053-1055], triphosgene [1056], phenyl chloroformate [1057], oxalyl chloride [1058, 1059], tri-chloroacetyl chloride [1060-1062], acetic anhydride [1063-1074], TFAA [1075-1082], phosphorus oxides [1083-1088], phosphorus oxychloride [1089-1098], phosphorus pentachloride [1099], triphenylphosphine/haloalkanes [1100-1103], thionyl chloride [1104-1118], p-tosyl chloride [1119-1124], triflic anhydride [1125-1127], chlorosulfonyl isocyanate [1128], the Burgess reagent [1129], phenyl chloro-thionoformate [1130], cyanuric chloride [1131-1134], carbodiimides [1135, 1136], CDC [1137], PyBOP [1138], AlCU/Nal [1139], and acetonitrile/aldehyde [1140], and by pyrolysis [1141]. 

Electrophilic attack on the C-3 urethane was achieved using chloro-sulfonyl isocyanate, which selectively transformed 510 to intermediate 514. Potassium iodide in acetone reacted with 514 to give allophanate (515), whereas isopropanol-collidine treatment of the same substance yielded 516. Phosphorus pentachloride reacted with protected cepha-mycin C (517) to form intermediate 518, which underwent solvolysis in methanol to 519 (25%). The chemoselective reaction of these electrophiles with urethane nitrogen stand in contrast to the selective acylation of amido nitrogen, which can be achieved with acid chloride and neutral acid scavengers (Karady et ai, 1972). 

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