American Chemical Society
ic051976l_si_001.cif (68.88 kB)

Facile Synthesis of Unsymmetrical 9-Phospha- and 9-Arsafluorenes

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posted on 2006-07-10, 00:00 authored by Armando A. Diaz, Jackie D. Young, Masood A. Khan, Rudolf J. Wehmschulte
Unsymmetrical 9-chloro-9-phosphafluorenes (dibenzophospholes) and 9-chloro-9-arsafluorenes (dibenzoarsoles) have been obtained by simple thermolysis of m-terphenyldichlorophosphines and -arsines in close to quantitative yields. The reaction temperatures are about 200 °C for the phosphines and 140 °C for the arsine, and the reactions are complete within 5 min. Alternatively, these compounds can be synthesized through an AlCl3-catalyzed Friedel−Crafts type ring-closure reaction at low temperatures, but this method suffers from difficult workup procedures. The P(As)−Cl functionality is readily alkylated. Methylation of m-xylyl derivative 4 afforded 1-(3,5-dimethylphenyl)-6,8,9-trimethyl-9-phosphafluorene, 11. The latter compound formed the complexes 11·Fe(CO)4, 12, and 11·RuCl26-p-cymene), 13, indicating its good donor properties. The new compounds have been characterized by 1H, 13C{1H}, and 31P{1H} NMR spectroscopy; mass spectrometry; and single-crystal X-ray crystallography in the case of 11, 12, and 13.