Investigations of the Synthesis of 1,2-Diphosphinines
摘要:
Several 1,2-disubstituted 3,6-bis(trimethylsilyl)-1,2-dihydro-1,2-diphosphinine complexes were prepared in a series of reactions starting from the palladium-catalyzed head-to-head dimerization of a 1-(2-ethoxycarbonylethyl)-2-trimethylsilylphosphirene W(CO)(5)-complex. The P-CH2CH2CO2Et bonds were cleaved by (BuOK)-Bu-t in THF to give the corresponding P-anions. The most significant products were the PCl-P(CH2CH2CO2Et) (4), PH-P(OH) (5), and PH-P(CH2Ph) (8) complexes. The thermolysis of the P(CH2Ph)-P(CH2Ph) complex (9) led to the corresponding phosphole complex 11 by extrusion of one phosphorus unit. Apparently, the postulated aromatic 1,2-diphosphinines are able to evolve toward other products via low-energy pathways.