Heterocyclic phosphonamidates

An unusual seven-membered diazaphosphatetrathia heterocycle (190) containing a chain of four sulfur atoms was obtained using diaryl or dialkyl phenyl phosphonamide 187 with sulfur monochloride in the presence of pyridine base (1993CC1684). A mechanism of the formation of 190 remains unclear but 190 was possibly formed via expected disulfide 188 which might be in equilibrium with bis(thionitroxide) 189 and the latter, in turn, could then further react with S2CI2 (Scheme 94). The extension sulfur chain was explained by the S2CI2 addition and... 

Phosphorus in both the 3 and 5 coordination states can be introduced into this class of heterocycle (Scheme 19). The diaminopyrimidine (189 R1 = R2 = H) reacts with triphenyl phosphite to give the phosphorus(III) derivative (95) <79Mi 713-01). By the use of phosphorus pentachloride the dichloro compounds (97) are formed <70K.GS7io>, whilst phenyl phosphonamide produces the derivatives (190) <63CI(L)819>. 

Metal-free azaphosphaannulation of phosphonamides (608) through intramolecular oxidative C-N bond formation led to production of novel phosphorus heterocyclic scaffolds, benzazaphosphol-3-one 1-oxides (609) (Scheme 177). ... 

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