A Reaction of Pyrylium Salts with Tris-hydroxymethylphosphine

Method A Reaction of Pyrylium Salts with Tris-hydroxymethylphosphine 

Our attempts as well as those of C. C. Price to react 2.4.6-triphenylpyry-lium salts with phosphine, phenylphosphine or tris-hydroxymethyl-phosphine in the hope of isolating phosphorins or their P-substituted derivatives were unsuccessful. In contrast, MarM applying essentially the same principle but using pyridine as base and solvent, succeeded by heating 2.4.6-triphenylpyrylium-tetrafluoro-borate 21 with tris-hydroxymethyl-phosphine 5. He was able to isolate 2.4.6-triphenyl-X -pbosphorin 22, m. p. 171—172 C, as the first X -phosphorin in 20-25% yield. 

Using this procedure, numerous other aryl-substituted X -phosphorins (see also Table 4), as well as the first alkyl-substituted analog, 2.4.6-tri-tert-butyl-X -phosphorin 24, were synthesized 

---