Poly-Nap

The homogeneous chiral phosphine/DPEN-Ru catalyst can be immobilized by use of polymer-bound phosphines such as polystyrene-anchored BINAP (APB-BINAP) [57, 98], Poly-Nap [99], and poly(BINOL-BINAP) [100], poly(BINAP) [101]. These complexes hydrogenate T-acetonaphthone and acetophenone with S/C of 1000-10 000 under 8 10 atm H2 to give the corresponding secondary alcohols in 84-98% e.e. The recovered complexes are repeatedly used without significant loss of reactivity and enantioselectivity. Immobilization allows the easy separation of catalyst from reaction mixture, recovery, and reuse. These advantages attract much attention in combinatorial synthesis. 

Examples of the anionic structures in polyphosphides, polyarsenides and poly antimonides. For comparison, recall the structures of red and black phosphorus and of arsenic (pp. 108, 109 and 110). Stereo image for NaPs... 

Ultimately, the ligand itself can be polymerized and used as both ligand and support in one [110]. Pu and coworkers have prepared the rigid chiral poly-BI-NAP ligand below (Fig. 42.17) and used it after treatment with Rh and Ru in asymmetric hydrogenations. The supported catalysts showed similar activities and enantioselectivities to their homogeneous analogues, with the benefit of... 

Figure 3. Experimental CD spectra of poly[Lys(Z) -1-nag la] in trimethyl phosphate at room temperature, [Nap] = 5.0x10 M. Numbers in the figure indicate the number of LysCZ) units, m.

DTPA = diethylenetriaminepentaacetic acid DL = detection limit EDTA = ethylenediaminetetraacetic acid ICP-MS = inductively coupled plasma mass spectrometry ISE = ion-selective electrode MCGE = membrane-coated graphite electrode NAP = 4-(/ -nitrophenylazo)-pyrocathecol PVC = poly(vinyl chloride RLS = resonance light scattering TBP = tri-n-butyl phosphate TOPO = tri- -octyl phosphine oxide XRF = X-ray fluorescence... 

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