- Selective O-alkylations with glycol chlorohydrins via the Mitsunobu reaction. A versatile route to calix[4]- and 1,1′-binaphthocrowns
-
Selective monoalkylation of p-tert-butylcalix[4]arene and BINOL with oligoethylene glycol chlorohydrins was achieved under the Mitsunobu protocol using DEAD/TPP. The method provides a simple access to ether precursors capable of cyclising to various crowns.
- Grün, Alajos,Koszegi, éva,Bitter, István
-
p. 5041 - 5048
(2007/10/03)
-
- [2]Catenane Assembly from Calix[4]arene Crown Ethers
-
A variety of novel calix[4]arene-incorporating crown ethers with or without intramolecular hydrogen bonding have been prepared by two efficient methods and utilized as donor rings to assemble calix[4]arene [2]catenanes based on π-stacking interaction between hydroquinone and bipyridinium units. Treatment of calix[4]arene crown ethers 4, 10a, or 10b, whose cone conformation was fixed by intramolecular hydrogen bonding within the calix[4]arene moiety, with dicationic salt 15·2PF6 and dibromide 16 afforded the corresponding [2]catenanes 17a·4PF6, 17b·4PF6, and 17b·4PF6in 20%, 53%, and 55% yields, respectively, whereas from the reactions of 15·2PF6and dibromide 16 in the presence of conformationally flexible 11 or 12 with a cone conformation kept by two propyl groups, [2]catenanes 18-4PF6 and 19-4PF6 were obtained in 12% and 6% yields. [2]Catenanes 21a· 4Cl, 21b·4Cl, and 21c·4Cl, incorporating calix[4]arene in both the donor and acceptor rings, were also successfully assembled from 10a or 10b, 16, and dicationic salts 20a·2PF6 or 20b·2PF6. The dynamic 1H NMR and absorption spectra of the [2]catenanes have been investigated, which revealed a strongest donor-acceptor interaction in 17a·4PF6 and that the cone [2]catenanes 17a-c·4PF6 can isomerize to the partial cone isomer at high temperature. The difference of the dynamic properties of these catenanes was discussed. The results demonstrate that catenation is one new general method to change the conformational distributions of calix[4]arenes.
- Li, Zhan-Ting,Zhang, Xiu-Lian,Lian, Xiong-Dong,Yu, Yi-Hua,Xia, Yi,Zhao, Cheng-Xue,Chen, Zhang,Lin, Zhi-Ping,Chen, Huan
-
p. 5136 - 5142
(2007/10/03)
-