Methylene phosphoranes rearrangements

Commercial development of calcium polyphosphate fibres Discovery of new class of aluminophosphate molecular sieves Preparation of first carbophosphene - (bis methylene phosphorane) Discovery of Phospha-Cope rearrangement Synthesis of first compound with an As=P bond Cyclo-P, triple decker compound made First asymmetric hydrogenation catalyst discovered (a metallophosphine complex)... 

The conversion of bis(2,4,6-tri-/ft/-butylphenyl)diphosphene 6 into diphosphirane 9 was accomplished by methylation with a large excess of methyl triflate in a concentrated dichloromethane solution to give the isolable phosphanylphos-phenium salt 7 (70%) and its subsequent deprotonation by diethylamine as a base. It was assumed that methylene(phos-phinidene)phosphorane 8 was first formed and then underwent an electrocyclic rearrangement to 9 (Scheme 2). 

The [(aryldiazenyl)methylene](tripheny])phosphoranes 1 afford in good yields the quina-zolin-4(3//)-one derivatives 2 via a facile thermally promoted rearrangement, withN=N bond cleavage and elimination of triphenylphosphane. ... 

Oxo-2,3-dihydro-1//-indazol-2-yl)niethylene](triphenyl)phosphoranes 9 undergo thermal and/or acid-catalyzed rearrangement to yield quinazolin-4(l//)-ones which more likely exist as 4(3/f)-tautomers 10 and triphenylphosphane. Compounds 9 are, in some cases, isolated as intermediates in a thermal rearrangement of [(aryldiazenyl)methylene](triphenyl)phosphoranes (cf. p72). 

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