Organophosphorus compounds; 52. Phosphatriafulvenes and their reactions with electrophiles

Article abstract of DOI:10.1055/s-1991-28399

Electrophilic reagents attack the phosphatriafulvenes 1a and 1b exclusively at the phosphorus atom. Hence 1b is methylated by methyl iodide to furnish the cyclopropenylium iodide 3 which, in turn, is converted to the triazine 6 by reaction with sodium azide. Ketenes 8 react with 1a through subsequent P → O silyl shifts to give the vinylphosphatriafulvenes 10. Isocyanates 13a and 13b behave analogously (→ 15). In the reactions of 1a with isothiocyanates 13c and 13d, in contrast, a P → N silyl shift is observed which leads to the formation of 16. Acetylenedicarboxylates 17 undergo insertion into the P/Si bond of the silylated phosphatriafulvene 1a (→ 19). In the case of the reaction of the mesitylsubstituted phosphatriafulvene 1b with 17, kinetically controlled formation of the dihydrooxophosphinines 20 takes place; at room temperature, the latter products undergo slow rearrangement to give the thermodynamically more stable isomers 21.