“…Furthermore, Mitsunobu cyclization of 2 4 with glycol was expanded to oligoethylene glycol analogues composed of O, S, and N atoms in the chain to produce various monocrowns such as 112 − 115 . On the contrary, reaction of disiloxane-capped 42 with several oligo(ethylene glycol) ditosylates using Cs 2 CO 3 as the base gave monocrowns 116 , which were desilylated by Bu 4 NF to give only 1,2-bridged monocrowns 117 (Scheme ) 34 Synthesis of Bis- and Monocrowns from 2 4 and 7 35 Formation of Thiacalixcrowns from 2 4 36 Reaction of 2 4 with Oligoethylene Glycols under the Mitsunobu Conditions To Give 1,3-Bridged Monocrowns 37 Synthesis of 1,2-Bridged Monocrowns from 42 …”
Section: 22 Complexation With Intra- and Intermolecular Bridged
Thiac...mentioning
“…Furthermore, Mitsunobu cyclization of 2 4 with glycol was expanded to oligoethylene glycol analogues composed of O, S, and N atoms in the chain to produce various monocrowns such as 112 − 115 . On the contrary, reaction of disiloxane-capped 42 with several oligo(ethylene glycol) ditosylates using Cs 2 CO 3 as the base gave monocrowns 116 , which were desilylated by Bu 4 NF to give only 1,2-bridged monocrowns 117 (Scheme ) 34 Synthesis of Bis- and Monocrowns from 2 4 and 7 35 Formation of Thiacalixcrowns from 2 4 36 Reaction of 2 4 with Oligoethylene Glycols under the Mitsunobu Conditions To Give 1,3-Bridged Monocrowns 37 Synthesis of 1,2-Bridged Monocrowns from 42 …”
Section: 22 Complexation With Intra- and Intermolecular Bridged
Thiac...mentioning
“…The analogous 25,26-bridged derivatives were obtained using difunctional alkylating agents. [36] To enhance the complexation ability of the thiacalixarenes, the lower rim hydroxyls were transformed into SH groups. [37] The acylation of 2 with N,N-dimethylcarbamoyl chloride produced the corresponding O-thiocarbamoyl derivative which was thermally converted into the S-carbamoyl derivative (the NewmanϪKwart rearrangement).…”
Section: Lower Rim Derivatization -Shaping Of the Molecular Skeletonmentioning
“…A number of thiacalix[4]arene-crowns have already been reported by several groups viz. 1,3-alternate thiacalix[4]arene-biscrowns, , diametrically bridged 1,3-alternate thiacalix[4]arene-monocrowns, , and proximally bridged thiacalix[4]arene-monocrowns . Thiacalix[4]arenes can adopt four different conformations viz.…”
Bridging of p-tert-butylthiacalix[4]arene afforded 1,3-dihydroxythiacalix[4]arene-monocrown-5 (3b), 1,2-alternate thiacalix[4]arene-biscrown-4 and -5 (4a,b), and 1,3-alternate thiacalix[4]arene-biscrown-5 and -6 (5a,b), depending on the metal carbonates and oligoethylene glycol ditosylates used. Starting from 1,3-dialkylated thiacalix[4]arenes, the corresponding bridging reaction gave 1,3-alternate, partial-cone, and cone conformers 10-19, depending on the substituents present. Temperature-dependent studies revealed that the conformationally flexible 1,3-dimethoxythiacalix[4]arene-crowns 10a-c exclusively occupy the 1,3-alternate conformation. Demethylation exclusively gave the cone 1,3-dihydroxythiacalix[4]arene-crowns (3a,c), which could not be obtained by direct bridging of thiacalix[4]arene. The different structures were assigned on the basis of several X-ray crystal structures and extensive 2-D (1)H NMR studies.
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