Reaction of dioxocalix[4]arene 7 with MeLi followed by 2-fold elimination of water yielded calixarene 8 possessing exocyclic double bonds at two adjacent bridges. Calixarene 8 exists in tetrachloroethane-d2 solution at rt, as a 2.3:1 mixture of the 1,3-alternate and partial cone conformers. Keto[n]calixarenes (n = 5, 6) were prepared via hydrolysis of the bromocalixarenes 11 and 12, followed by CrO3 oxidation of the respective hydroxymethylene derivatives. Addition of MeLi to the ketocalix[n]arenes (n = 4, 5 and 6) followed by elimination of water yielded the corresponding calix[n]radialenes. Calix[5]- and calix[6]radialenes adopt in the crystal irregular alternate (i.e., noncone) conformations.
A new isomer, not previously detected, is the kinetic product of the octabromination (NBS, CH 2 Cl 2 , rt, 60 W Vis irradiation) of p-tert-butylcalix [8]arene octamethyl ether. On the basis of the signal pattern in the NMR spectrum, and the splitting of methoxy signals in the presence of a chiral solvating agent, the isolated product is assigned as one of the two possible achiral forms of C s symmetry, where the mirror symmetry operation bisects two opposite aryl rings.
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