Phosphorinium salts

A niunber of 3-aryl- -phosphorins, 3-aryl-A --phosphorins, and 3-aryl-A -phosphorinium salts have been synthesized from oxaphosphorinium bromides (9). Spectral data indicate that in polar solvents l-chloro-3-phenyl-1-tert-butyl--A -phosphorin (10) is in equilibrium with 3-phenyl-1-fert--butyl-A -phosphorinium chloride (11). Thermolysis of derivative (10 Ph=aryl) yields the 3-aryl-A -phosphorin (12), which on oxidative alkoxylation with Hg(OAc)2/ntethanol affords the 3-aryl-1,1-dimethoxy-A -phosphorin (13) (Markl,... 

X -phosphorins have physical properties which are rather similar to those of pyridines. But the chemistry of X -phosphorins is very different, due mainly to the phosphorus atom which can easily lose one electron to produce a stable radical cation, or accept one or more electrons to yield a radical anion, dianion or radical trianion. Nucleophiles add to stable X -phosphorin anions. In contrast to pyridine chemistry, no stable X -phosphorinium compound (corresponding to a N-alkyl-pyridinium salt) could be isolated. Instead the electron shell of phosphorus is enlarged by addition of an electrophile yielding a X -phosphorine derivative. 

TetraphenyIphosphorinium tetrachloroaluininate (38) the first phosphorinium (phosphininium) salt analogous to the pyridinium salts is obtained by treating 1-fluoro-1,2,4,6--tetraphenyl-A -phosphorin (37) with aluminium trichloride in methylene dichloride at -78°. Salt (38) on treatment with MeOH, EtOH, PhLi, or Cl affords the corresponding derivative (37 F=MeO, EtO, Ph, or Cl) (T.N. Dave, Kaletsch, and Dimroth, Angew. Chem., 1984, 96, 984). 

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See also in sourсe #XX -- [ ]

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