Organophosphorus compounds; 72. The tri-tert-butylcyclopropenyl group as a steric protecting function for 1-phosphaallenes

Article abstract of DOI:10.1055/s-1993-26036

When the tri-tert-butylcyclopropenylphosphane 5 is allowed to react with ketenes 6, the cyclopropenyl(silyl)vinylphosphanes 7 are obtained. Subsequent acylation proceeds via silyl exchange to furnish the phosphanes 8 while methanolysis gives rise to the secondary phosphanes 9 by way of P/Si bond cleavage. Sodium hydroxide catalyzed elimination of hexamethyldisiloxane from 7 results in the formation of the 1-phosphaallenes 10. The P/C double bonds of the latter can be saturated by either 1,2-addition (→ 11, 12) or by oxidative addition (→ 13) followed by addition of water (→ 14). Complexation of 10 with the metal fragments W(CO)₅ or Fe(CO)₄ moieties yields the novel metal complexes 15 and 16.