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Conformations of the Acyl Esters of p-Tert-butylcalix[4]arene and Calix[4]arene
No Kwanghyun,Koo Hee Jung Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.6
Tetra acyl esters of p-tert-butylcalix[4]arene and calix[4]arene, including acetyl, propionyl, butyryl and isobutyryl, are synthesized and their conformations are inferred from $^1H-NMR$ and $^{13}C-NMR$ spectra. The conformer distribution is affected by the presence of t-butyl group, whereas the acylation products of p-t-butylcalix[4]arene are the cone conformers, those of calix[4]arene are mostly partial cone and/or 1,3-alternate conformers. The conformational outcome is also affected by the method of preparation, the NaH-induced reaction is prefered to the acid-induced reaction for cone and partial cone. Interestingly, 1,2-alternate conformer was isolated in 14% yield from the butyrylation of calix[4]arene.
The Synthesis of Selectively Substituted p-Acethylcalix[4]arene
Kwanghyun No,Mi Sook Hong Korean Chemical Society 1990 Bulletin of the Korean Chemical Society Vol.11 No.1
A method is described for the selective functionalization of calix[4]arene at the para positions of the phenyl rings. The diametrically substituted calix[4]arene dimethyl ether 3, obtained from the treatment of calix[4]arene 2 with methyl iodide in the presence of $K_2CO_3$, is converted to the diacetyloxy calix[4]arene dimethyl ether 4. This compound undergoes Fries rearrangement to yield the diametrically p-diacetylcalix[4]arene dimethyl ether 5 in 68% yield.
Conformations of 25,27-Diacyloxy-26,28-dialkyloxycalix[4]arenes
Kwanghyun No,Hee Jung Koo,Min Seong Lee Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.9
1,3-Dimethyl and dipropyl ethers of p-t-butylcalix[4]arene and calix[4]arenes have been converted to the corresponding diesters, acetate and propionate, and their conformations are inferred based on the $^1H$ and $^{13}C$ NMR spectra. The presence of t-butyl groups is effective in maintaining the cone conformation on derivatization.
The Syntheses of p-Acylcalix[4]arenes
Kim, Younhee No, Kwanghyun 숙명여자대학교 자연과학연구소 1989 자연과학논문집 Vol.- No.1
Starting with readily available p-tert-butylcalix[4]arene 3 tert-butyl groups are removed by AlCl₃-catalyzed de-alkylation reaction, and the calix[4]arene 4 formed is converted into the tetraacyl esters. These compounds undergo Fries rearrangement to yield p-acylcalix[4]arenes. p-Acetyl, p-propionyl, p-butyryl, and p-benzoylcalix[4]arene 10, 11, 12 and 14 are synthesized in 70-80% yields by treatment of the corresponding esters 5, 6. 7 and 9 with AlCl₃ in nitrobenzene. When the tetraisobutyryl ester 8 was treated with the same condition, only two isobutyryl groups were rearranged to the para-positions of calix[4]arene, and remaining two groups were simply cleaved.
Synthesis and X-ray Crystallographic Characterization of p-Diacetylcalix[4]arene
Park, Young Ja No, Kwanghyun Shin, Jung Mi 숙명여자대학교 자연과학연구소 1992 자연과학논문집 Vol.- No.3
A simple route is described for the selective functionalization of calixarene at the para positions of phenyl rings. Calix[4]arene tetraacetate 2, obtained from the treatment of calix[4]arene with acetic anhydride, undergoes Fries rearrangement to yield the diametrically para substituted p-diacetylcalix[4]arene 3 in 80% yield. The crystal and molecular structure has been determined by X-ray diffraction method. The crystals are orthorhombic, space group Pna2₁, with a=11.121(3), b=10.374(3), c=21.690(6) Å and Z=4. The structure was solved by direct method and refined by full-matrix least-squares methods to final R of 0.036 for 1795 observed reflections. Each hydroxyl hydrogen atom is disordered over two positions. The macrocycle exists in the cone conformation which is determined by the strong circular intramolecular flip-flop type hydrogen bonds of phenolic OH, while crystal packing effects of the diametrically para-acetyl substituents seem to be responsible for the distortion of the cone conformation.
Synthesis and X-Ray Structure of 25-Acetoxy-26, 27, 28-trimethoxycalix[4]arene
Park, Young Ja No, Kwanghyun Song, Boo-Hee Rhim, Soo Kyung 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5
25-Acetoxy-26,27,28-trimethoxycalix[4]arene was synthesized by the treatment of calix[4]arene trimethyl ether with acetyl chloride in the presence of NaH. The solution conformation was inferred as a partial cone conformation based on the ¹H-and 13C NMR spectra. The crystal structure has been determined by X-ray diffraction method. The crystals are monoclinic, space group P2/n, a=8.186 (1), b=17.137 (2), c=19.878 (3) Å, β=95.67 (1)°, Z=4, V=2774.90 Å, Dc=1.22g cm-³, Dm=1.23g cm-³. The intensity data were collected on an Enraf-Noninus CAD-4 Diffractometer with a graphite monochromated Cu-Ka radiation. The structure was solved by direct method and refined by full-matrix least-squares methods to a final R value of 0.054 for 3675 observed reflections. The molecule possesses a partial cone conformation with one flattened pheyl unit, in which one anisol ring, distal to the ester ring, is inverted. The acetoxyphenyl ring is flattened.
Cone-Structured Deep-Cavity Formation at Upper-Rim of Calix[4]arene Tetrahexyl Ether
Paek, Kyungsoo Ihm, Hyejae No, Kwanghyun 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5
Conclusively we observed that the Pd(0)-catalyzed coupling reaction of ρ-bromocalix[4]arene tetrahexyl ether 3 with arylboronic acids having various functional groups, e.g. even a sterically hindered ortho substituent can be used as a general method to get a calix[4]arene derivative having conestructured rigid deep-cavity. Molecular recognition studies and further functionalizations of obtained hosts are in progress.
헥산산 파라-t-부틸캘릭스[4]아렌의 형태에 관한 연구
盧光鉉,金尹善 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5
p-Tert-butylcalix[4]arene was refluxed with hexanoyl chloride in the presence of NaH or AlCl₃produced calix[4]arene tetra hexanoate 2. When the reaction was carried out at room temperature only two distal OH groups were acylated to afford calix[4]arence di-ester 3. The conformations of both compounds were determined as cone from the ¹H-and 13C-NMR spectra.
盧光鉉,權景味,金鐘銀 숙명여자대학교 자연과학연구소 1995 자연과학논문집 Vol.- No.6
Four calix[4]arenes having two different substituents at upper rim in AAAB fashion were synthesized in 22-38% yield by the '3+1' coupling reaction between trimer of p-substituted phenol (AAA) and bishydroxymethylated p-substituted phenol (B). The structure of calix[4]arene was confirmed from the ¹H and ?? NMR spectra.