Phosphorus sulfur trichloride amides

Phosphorus trichloride is the starting material used most frequently for the preparation of the esters, amides and anhydrides of phosphoric and phos-phorothioic acids. It can be oxidised to phosphoryl chloride (4) and, heated with sulfur in the presence of a catalyst, to thiophosphoryl chloride (5) (Perot, 1962). 

Further studies by Spry (1975a,b) showed that treatment of the 3-formyl-2-cephem (247) with N-methylhydroxylamine gave the N-meth-ylnitrone (248). Sulfur oxidation and concomitant isomerization of the double bond then yielded the nitrone sulfoxide (249) which upon reaction with phosphorus trichloride in DMF, followed by ester cleavage, provided the 3-carboxamide-3-cephem-4-carboxylic acid (251). Alternatively, the reaction of the nitrone-2-cephem compound (248) with acetic anhydride furnished a mixture of the amide (250) and the imide (252). Both the amide and the imide, after isomerization of the double bond to 3-cephem and ester cleavage, gave the corresponding A -methylamide (251). 

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