Synthesis, characterization of calix[5]azulene and its complexation with pyridinium salts

Persistent azulene α-carbocations: synthesis from aldehydes, spectroscopic and crystallographic properties

“…13 This second reduction is enabled by the stability of cationic intermediate 13 (Scheme 1b). The intermediacy of cations such as 10 also enables reactions such as hydration of 1-azulenylalkynes, 14 formation of azuleno[2,1- b ]thiophenes, 15 formation of calix[ n ]azulenes, 16 pyrrole-mediated azulene decarbonylation, 17 and protection of thiols with azulene-based protecting groups. 18 If cations of type 10 possess R 1 and R 2 substituents which are sufficiently cation-stabilising, then they may be isolable as stable salts with non-nucleophilic anions.…”

Synthesis of calixresorcarenes using magnetic poly triazine-benzene sulfonamide-SO3H

“… 3 Moreover, many researchers have concentrated on the phase transfer catalyst activity, 4 encapsulation, 5 and supramolecular chemistry of calix[4] arene and its derivatives. 6 The functionalization of calix[4]arene has attracted considerable interest, 7 from characterization such as the ease of functionalization or modification, the flexibility and rigidity of the four different three dimensional conformations. 3 For the synthesis of various calixarenes/calixresorcinarenes, the reaction of resorcinol with benzaldehyde derivatives is a particularly important method.…”