882883-33-2Relevant academic research and scientific papers
Template synthesis of 1,4,7-triphosphacyclononanes
Edwards, Peter G.,Haigh, Robert,Li, Dongmei,Newman, Paul D.
, p. 3818 - 3830 (2007/10/03)
Iron(II) templates based on a [(η5-CpR)Fe] + core have been employed for the successful synthesis of 1,4,7-triphosphacyclononane derivatives (9-aneP3R′3) from a range of appropriately functionalized coordinated diphosphines and monophosphines. 1,2-Diphosphinoethane (1,2-dpe) or (2-phosphinoethyl)- phenylphosphine (Phdpe) undergo a base-catalyzed Michael-type addition to trivinylphosphine, divinyl-(benzyl)phosphine, ordivinyl(phenyl)phosphine in [(η5-CpR)Fe(diphosphine)(monophosphine)]+ complexes (2a-j) to give [(η5-CpR)Fe(9aneP 3R′3)]+ derivatives (4a-j) containing coordinated triphosphacyclononanes bearing one (with Phdpe) or two (with 1,2-dpe) secondary phosphine donors. The rates of macrocyclization show a dependence on the nature of the substituent(s) R on the cyclopentadienyl ligand with increased rates being observed along the series R = H5 3Si)H 4 3Si)2H3 ≈ Me 5. For coupling reactions with trivinylphosphine, a pendant vinyl function remains in the macrocyclic product (4a-g) which is readily hydrogenated to the corresponding ethyl derivatives (5a-g). Further functionalization of coordinated secondary phosphines in the initially formed macrocycles (5a-g) is achieved by proton abstraction followed by addition of the appropriate alkyl halide electrophile and gives rise to tritertiary-triphospha-cyclononanes (7a-g, 71, 7m). All new complexes have been fully characterized by spectroscopic and analytical methods in addition to the structural determination by single-crystal X-ray techniques of [η5-(Me3Si)2C 5H3)Fe(9-aneP3H2C2H 3)]PF6, 4c, and [η5-Me3SiC 5H4)Fe(9-aneP3Et3)]BF4, 7b. 1,4,7-Triethyl-1,4,7-triphosphacyclononane is released from its metal template (7a, 7b) by treatment with either H2O2 or Br 2/H2O to give the trioxide 9-aneP3(O) 3Et3 (8). Attempts to recover the trivalent phosphorus species, 1,4,7-triethyl-1,4,7-triphosphacyclononane, from the trioxide by reduction proved unsuccessful.
