Calixarenes. 17. Functionalized calixarenes: the Claisen rearrangement route

Abstract

5,11,17,23-Tetrabromo-25,26,27,28-tetrahydroxycalix[4]-arene (31). A solution of 0.5 g of 5,11,17,23-tetrabromo-25,26,27,28-tetramethoxycalix[4]arene (15) in 40 mL of benzene was treated dropwise with 15 mL of BBr?' in CH2C12, and the mixture was stirred at r c " temperature for 18 h in an atmosphere protected from moisture. The reaction mixture was poured into 100 mL of H20, stirred for 1.25 h, and the organic layer was evaporated and triturated with acetone to leave 0.39 g (84%) of a white powder. Crystallization from pyridine/toluene yielded a yellow powder as the first fraction and a white powder as the second fraction: mp >480 "C; IR (KBr) 3135 cm-' (OH stretching); 'H NMR (pyridine-d,) b 9.72 (s, 4, OH), 7.25 (s, 8, Ar H), 4.0 (br (37) Tashiro, M.; Yoshiya, H.; Fukatas, G.Methods for the preparation of a variety of para-substituted calix[4]arenes via the Claisen rearrangement route are described. Starting with the readily available p-tert-butylcalix[4]arene 1, the tert-butyl groups are removed by an AlCl,-catalyzed retro-Friedel-Crafts reaction, and the calix[4]arene 2 that is formed is converted to the tetraallyl ether 3. This compound undergoes a heat-induced Claisen rearrangement to yield p-allylcalix[4]arene 4, which is a useful starting material for the introduction of functional groups. Along one route, the tosylate of 4 is ozonized to the aldehyde 7, the aldehyde is reduced to the alcohol 8, the alcohol is converted to the bromide 10 and then to the azide 11, and the azide is reduced with diborane to p-(2-aminoethyl)calix[4]arene 12, a compound of interest as a chelating species. Along a second route, the tosylate of 4 is rearranged to p-(l-propenyl)calix[4]arene 16 and ozonized to p-formylcalix[4]arene 17 from which the oxime 18 can be prepared.

Synthesis of calix[4]arenes modified with germanium‐containing side chains on the upper rim

“…7 Trimethylgermylpropanoyl chloride (9) was prepared in a similar manner to that of triethylgermylpropanoyl chloride (8). 8 The structures of these new calixarene derivatives were confirmed by elemental analysis and 1 H and 13 C NMR spectroscopy, all of which were consistent with the assigned structure.…”

Research on Synthesis of New Azo Calix[4]arene and its Dyeing Properties

“…[4]arene and calix [4]arene Refer to the references [12,13] to synthesize the tert-butyl calix [4]arene, and refer to the reference [14] to synthesize the calix [4]arene.…”

Synthesis of mono- and diboronic acid calix[4]arene receptors

“…15,16 Using similar methodology to that described for the p-tert-butyl derivative 7, selective boronation to the p-Hcalix [4]arene 10 was accomplished as shown in Figure 3. Monoboronic acid 11 and diboronic acid 12 calixarenes were prepared in this manner.…”