Double Parallel Inversion

The taloside derivatives can be acquired starting from 34 and 36 via the inversion of the 2-position, or starting from 37 via the double parallel inversion of 2- and 4-positions, if the equatorial ester group in the 3-position is able to activate the epimerization of the neighboring 2- and 4-positions at the same time (Figure 15). On the other hand, the... 

Scheme 14. Double parallel inversion reagent and conditions.

Based on the efficient multiple carbohydrate esterifications and Lattrell-Dax carbohydrate epimerization, novel and convenient double parallel- and double serial inversion methods have been developed, by which methyl p-D-mannosides and methyl P-D-talosides have been efficiently synthesized in very high yields at very mild conditions in few steps. The results also indicate that an ester group can, either in parallel or serially, induce its two neighboring groups in the epimerization reacriom... 

Fig. 4.3-9 the A -.splitting in the other band is not resolved). The second parallel band (i/[ at 3336.2 cm ) is split much less, due to inversion doubling with AF = 1.8 cm. The P 4 fundamental at 1627 cm is a perpendicular band with the Q branch lines compressed in a smaller spectral interval compared to that of the CHyTspectrum. Another example of a spectrum which resembles those recorded with tower resolution, is the gas phase spectrum of benzene shown in Fig. 4.3-10. The fingerprint region below 2000 cm exhibits the mo.st intense fundamental (v ), which is a parallel band, at 671 cm , The two perpendicular bands at 1485 cm (vis) and 1037 cm (ph) demonstrate similar features.

Possible synthetic routes to frinvestigated using the /J-hydroxy-t/3-phosphane oxide alkene inversion procedure. A stepwise approach via the epoxy-trans-cyclononene derivative failed. However, consecutive double elimination involving the bis-/ -hydroxy-) 5-phosphane oxides 11 and 12 gives cis- and trails- 1,2-di-vinylcyclopentanes which are believed to be formed by a rapid Cope rearrangement of parallel and crossed r[Pg.362]

The inverse boundary capacitance Q is essentially the sum of the inverse contribution of the space charge layer and the rigid double layer and usually dominated by the first contribution. Since the effective dielectric permeabilities of bulk and boundary are comparable, the ratio cjc. significantly differs from unity (it is typically of the order of LIX, L being the sample thickness, and X the Debye length). This explains (i) why for comparable and values the relaxation times are typically drastically different, and (ii) why the uncertainty whether Q is in parallel to the whole MX-part of the cell or only to the proper bulk part as assumed in Eq. (62), corresponds to a quantite negligeable. Note that in a polycrystalline material 1/Q as well as are—if they... 

---