106006-58-0Relevant academic research and scientific papers
Synthesis, isomer separation, and metal complexation studies of aza- and oxaphosphands, a class of hard/soft dinucleating phosphine macrocycles
Wei, Liwen,Bell, Andrew,Ahn, Kwang-Hyun,Holl, Mark M.,Warner, Steve,Williams, Ian D.,Lippard, Stephen J.
, p. 825 - 837 (2008/10/08)
Two hybrid, asymmetric phosphine macrocycles, [22]P2O2N3 and [21]P2O5, have been synthesized in high-dilution macrocyclization reactions. In THF solution, 1,3-bis(phenylphosphino)propane and 6,9,12-tris(p-tolylsulfonyl)-1,17-dichloro-3,15-dioxa-6,9,12-(Chemical Equation Presented) triazaheptadecane react in the presence of lithium hexamethyldisilazide (LHDS) giving 16,20-diphenyl-4,7,10-tritosyl-1,13-di-oxa-16,20-diphospha-4,7,10- triazacyclodocosane, [22]P2O2N3Ts3, in good yield (68%). Similarly, oxaphosphand [21]P2O5, 1,4-diphenyl-7,10,13,16,19-pentaoxa-1,4-diphosphacycloheneicosane, was prepared under high-dilution conditions from 1,2-bis(phenylphosphino)ethane and 1,19-ditosyl-1,4,7,10,13,16,18-heptaoxanonadecane. The two [22]P2O2N3Ts3 diastereoisomers, anti (racemic) and syn (meso), were separated through selective precipitation of their respective nickel complexes, anti-〈P2NiCl2|N3〉Ts3 and syn-〈P2Ni(NCS)2|N3〉Ts3, and subsequent cyanolysis to remove nickel. The oxaphosphand [21]P2O5 diastereoisomers, anti and syn, were separated as their nickel thiocyanate complexes, anti-〈P2Ni(NCS)2|O5〉 and syn-〈P2Ni(NCS)2|O5〉, by using preparative flash chromatographic techniques and subsequently demetalated with cyanide ion. 31P(1H) and 13C{1H} NMR data established the isomeric purity of both racemic and meso forms of the macrocycles. The diastereomers anti- and syn-[22]P2O2N3Ts3 isomerize upon fusion to give an approximately equimolar isomeric mixture. Removal of the protecting tosyl groups was effected at -78°C by sodium naphthalenide in glyme (DME) containing tert-butyl alcohol as a proton source to afford the azaphosphands [22]P2O2N3. The ligands anti- and syn-[22]P2O2N3Ts3 and anti- and syn-[21]P2O5 form complexes with group 10 transition metals to yield species of the general formulas anti- and syn-〈P2M(XY)|N3〉Ts3 and anti- and syn-〈P2M(XY)|O5〉. In no case does the protected amine portion of the macrocycle bind to transition-metal centers. The structure of anti-〈P2PdCl2|O5〉 was determined by single-crystal X-ray diffraction analysis. Resolution of anti-〈P2Ni(NCS)2|H2N 3〉(NCS)2 enantiomers was achieved by the method of Pasteur. From solutions of dissolved single crystals in 1:1 CH3CN-CH3OH the following specific rotations were found: [α]25D = +15 ± 2°; [α]25D = -18 ± 2°.
