Cage systems synthesis

Scheme 4.31. Synthesis of carbo- and hetero-cage systems.

Dicyanopyridazine 4-145 has been used for the synthesis of carbo- and het-ero-cage systems employing nonconjugated dienes such as cyclooctadiene 4-146, or 4-148 or 4-150 to give 4-147, 4-149 and 4-151, respectively (Scheme 4.31) [50]. In a similar way, dihydrofurans, dihydropyrans, pyrrolines, and enol ethers have also been used [51],... 

In this section, the synthesis and some chemistry of cage systems involving negatively charged boron atoms carrying, three phosphine groups coordinated to Co, Fe, Sn, Tl, Ru, Ir in different valence states are considered. 

Application of the template encapsulation procedure to the rigid cyclohexanediaminate Ze(3-[Co(chxn)3] cation has yielded a high symmetric cage systems [107]. For the synthesis of the diaminocyclohexane sarcophaginates, the condensation procedure was modified (pH ll-rl2 and elevated temperatures) compared with that for ethylenediamine sarcophaginates. 

In a seminal paper appearing in 1969, Dietrich, Lehn, and Sauvage" described the first synthesis of a series of cryptands of the type 14. In part, it was the known alkali metal binding (and membrane transport behavior) of the natural antibiotic ionophores that provided the inspiration for the design of these then novel cage systems." ... 

The particle size of Pd and Pt phases encapsulated in zeolite hosts can be controlled by chosing appropriate reduction conditions for the ion exchanged, dehydrated precursor form.27 28.29 Based on x-ray diffraction studies, a bidisperse distribution of Pd particles appears to be typical In addition to particles 10-20 A in size, a second Pd phase was assigned to Pd atoms in the cage systems. In the following we describe the synthesis and characterization of Pd ensembles, consisting of 2 to 4 correlated atcnns, which are stabilized at room temperature in an open, chemically accessible zeolite matrix. Characterization of the clusters was done by means of x-ray absorption spectroscopy (EXAFS). ... 

There is another type of multiple thermal Diels Alder reaction in which the initial monoadduct is involved, either directly or after one transformation, in a second cycloaddition that affords the final polycyclic compounds. These methodologies have been used especially in the synthesis of polycyclic cage compounds. Paquette was the first to report the conversion of 9,10-dihydroful-valene into polyfused cyclopentanoid systems [124],... 

Two further unsaturated cages. Each of the systems discussed so far involves reaction of an electrophilic reagent with non-coordinated nucleophiles appended to metal-bound ligands. In contrast, in the following synthesis, cage formation occurs via an internal rearrangement of an Fe(u) complex of type (151) (Herron et al., 1982). Complexes of type (151) have already been discussed in Section 3.5. Treatment of these... 

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