Kinetically and thermodynamically controlled synthesis of tetraoxa[14]metacyclophanes and hexaoxa[16]metacyclophanes

Oxacalix[n](het)arenes

“…Konishi et al recently performed an investigation of kinetic and thermodynamic reaction conditions for the synthesis of oxacalixarenes. 17 For this purpose, they designed an oxacalix[4]arene bearing intra-annular n-propyl groups on the resorcinol building block. Since the bulky propyl chain is unable to pass through the central annulus of the oxacalix[4]arene, two conformational isomers 16a,b could be formed (Fig.…”

Synthetic Exploration of Oxacalix[2]arene[2]quinazolines

“…For the reaction using CsF (2 equiv.) base, a shorter reaction time (1 h) resulted in a similar mixture of linear oligomers (53 % 4 , 20 % 5 ; Table 1, Entry 4) 8h. The combination of Cs 2 CO 3 or CsF base and DMSO as the solvent also caused a decrease in the oxacalix[4]arene yield (to 7 and 54 %, respectively; Table 1, Entries 5 and 6) 8o.…”

“…On applying triethylamine (2.2 equiv.) as an organic base in acetonitrile at reflux (Table 1, Entry 7),8h no macrocyclic species were formed and only linear oligomers were observed, that is, mainly 4 (30 %) and 5 (63 %).…”

Synthesis of Polyfluorinated Thia- and Oxathiacalixarenes Based on Perfluoro-m-xylene

“…So, the chemical shift of the hydrogen atom H-28 in CDCl 3 is 5.45 ppm for 8 and 5.08 ppm for 9, and in (CD 3 ) 2 CO 6.25 ppm for 8 (Figure 2a) and 6.00 ppm for 9. The presence of an upfield shift of the inner-rim protons in the 1 H NMR spectra indicates that dioxadithiacalix [4]arenes 8-9, as well as tetraoxacalixarenes [26], have a 1,3-alternate conformation in solution. In the 1 H NMR spectra of tetraoxadithiacalix [6]arene 12, a noticeable upfield shift of the inner-rim protons (H-39,42; δ 6.14 ppm in acetone-d 6 , Figure 2b) of the resorcinol fragment is also observed, and it is practically absent in the 1 H NMR spectra of tetraoxathiacalixarene 15 (H-33,35; δ 6.92 ppm in acetone-d 6 , Figure 2c).…”

“…By column chromatography on silica gel using CCl 4 and CHCl 3 as eluents, 0.68 g of the solid product containing (GC-MS) 93% tetrathiacalixarene 1 was isolated. 5,11,17,23,25,26,27,6,10,12,16,18,22,24-octakis(trifluoromethyl)-2,8,14, 20-tetrathiapentacyclo[19.3.1.1 3,7 .1 9,13 .1 15,19 ]octacosa-1(25),3 (28),4,6,9(27),10,12,15(26),16,18, 21,23-dodecaene 1:…”