Phospholes with reduced pyramidal character from steric crowding III NMR and X-ray diffraction studies on 1-(2,4,6-tri-isopropylphenyl)-3-methylphosphole
摘要:
The 2,4,6-tri-isopropylphenyl substituent was placed on the phosphorus of a phosphole to reduce the pyramidal character. That this was accomplished was revealed by single crystal X-ray diffraction analysis; with respect to the plane of C-2-P-C-5 in the phosphole ring, the ipso carbon of the benzene ring was deflected by only 58.0 degrees, whereas the deflection is 66.9 degrees in the uncrowded 1-benzylphosphole. This proves that the concept of reducing the pyramidal character (with the goal of increasing the electron delocalization) through steric crowding can be realized. In the crystal the two rings are in orthogonal planes, but this relation is not retained in solution; NMR studies show that the two edges of the benzene ring, as well as the 2,6-isopropyl groups, are identical.
The Preparation and Anticancer Activity of Some Phosphorus Heterocycles
作者:Harry R. Hudson、György Keglevich
DOI:10.1080/10426500801938592
日期:2008.8.4
Methods for the preparation of somephosphorus heterocycles are reviewed, together with a preliminary report of their activity in vitro against the NCI 60-cell line panel of human tumour cells. The most active compound, a dimer of 3-methyl-1-(2,4,6-triisopropylphenyl)phosphole oxide, showed GI50 values in the micromolar region against leukaemia cell lines RPMI-8226 and SR, non-small cell lung cancer
The reaction of 1-(tri-tert-butylphenyl)phosphole (1) with phosphorus tribromide gave the 3-dibromophosphino intermediate (2) selectively that was useful in the synthesis of phosphonic amides 4, H-phosphinic amide 6 and H-phosphinates 8. A similar transformation of the 1-(triisopropylphenyl)phosphole (9) led to a 2-substitution furnishing phosphonic amides 12 or H-phosphinates 14. The phosphorylated
A new reaction of 1-(2,4,6-trialkylphenyl)phospholes with heteroaromatic character; aromatic electrophilic substitution under the conditions of Friedel–Crafts acylation
Two (trialkylphenyl)phospholes (1 and 4) with significant heteroaromatic character due to the flattened P-pyramid underwent Friedel–Craftsacylation with acyl halides to afford 2-acylphosphole derivatives (e.g. 2 and 6, respectively); the 2-acyl-5-arylphosphole by-product 7 may have been formed by sigmatropic rearrangement through 2H-phosphole 9 or dibromophosphorane 12.
Diels–Alderreaction of the title phospholes and N-phenylmaleimide afforded, surprisingly, a mixture of endo and exo fused cycloadducts with the P-aryl substituent anti to the double bond giving, after oxidation the corresponding P-oxides. The P-center of the exo ring fused P-oxides was found to be inverted under the conditions of the oxidation. The cycloaddition of triisopropylphenylphosphole with