Cationic organic substructure

In ditopic hosts 65 the two cationic substructures are linked by a naphthy-lene diether. Schmidtchen observed the formation of 1 1 phosphoester complexes in organic solution with disilylether 65a and in water with diol 65b. The flexible skeleton enables the hosts to wrap around phosphate forming two pairs of hydrogen bonds with perpendicular main planes as schemed in formula 66 for the 5 -TMP complex [98]. Similarly, the complexation of AMP derivatives, NAD, and other phosphates by the related host 16 (Sect. 2) and its desilylated modification have been reported recently [99]. 

The interface between organic and inorganic substructures has been manipulated in the preparation of hybrid materials which exhibit composite or even new properties, representative examples of which include zeolites [34-36], mesoporous oxides of the MCM-41 class [37] and metal phosphates with entrained organic cations [38-55] (Refs 39-55 are representative examples of the expanding family of oxovanadium-phosphate-organic cation materials). 

Another possibility would be the use of allylic esters, which after a gold-catalyzed cycloisomerization with the carbonyl oxygen atom as the nucleophile deliver activated allylic intermediates which at the same time contain a vinylgold substructure. After transfer of an allyl cation to palladium(O), an oxidative addition to palladium, the vinylgold intermediate could transfer the organic moiety to palladium(II). A final reductive elimination would close the catalytic cycle. At the same time, no halide that potentially could deactivate the cationic gold(I) catalyst would be present. Indeed, Blum et al. [30] presented such systems. But... 

---