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Synthesis and Characterization of New Calixarenes from Bisphenol A
안교한,김성곤,유종선,An, Gyo Han,Kim, Seong Gon,Yu, Jong Seon Korean Chemical Society 2000 Bulletin of the Korean Chemical Society Vol.21 No.8
The synthesis of bisphenol A-derived calixarenes has been studied by changing the protecting group of the phe-nol moiety and reaction conditions. Depending on the protecting groups,the corresponding calix[6,7,8]arenes are obtained in different rat ios. For example, whcn mono-p-tert-butyldimethylsilyl-protected bisphenol A is treated with paraformaldehyde and a catalytic amount ofaqueous KOH in refluxing p-xylene with a Dean-Stark water collector for 36 h, the corresponding calix[8]arene, calix[7]arene, and calix[6]arene are producedand separated in the ratio of about 3 : 2 : l and with overall 63% yield. The calixarenes are characterized by NMR spectroscopy and mass analysis. The X-raycrystal structure of the calix[8]arene shows a pleated loop confor-mation, stabilized by intramoIecular hydrogen bonding between the inner phenolic hydroxy groups.
Hidekazu Miyaji,안교한,박수문,김대식,Byoung-Yong Chang 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.12
Described are the electrochemical and 19F NMR detection of anions, ion-pairs, and zwitterionic L-phenylalanine with the ferrocene-based hetero-ditopic receptor. A cyclic voltammetric study shows that the receptor induces a positive shift in the ferrocene oxidation potential upon binding of a potassium cation, whereas it induces a negative shift upon binding of an acetate anion, both of which can be reversed. Also, the redox potential shifts were dependent on ion-pairing interactions. Furthermore, direct detection of an amino acid in its zwitterionic form is demonstrated by 19F NMR spectroscopy in aqueous media.
A Synthetic Study on ($\pm$ )-Podosporin A
유동진,최원우,이석종,안교한,Yu, Dong Jin,Choe, Won U,Lee, Seok Jong,An, Gyo Han Korean Chemical Society 1996 Bulletin of the Korean Chemical Society Vol.17 No.2
The synthesis of common skeleton of podosporin A and aureol was studied through cationic olefin cyclization as a key step. The generation of thermodynamic silyl enol ether or enol acetate under known conditions gave regioselectivity of 88:12. The enolate alkylation of 2,3-dimethylcyclohexanone with 2,5-dimethoxybenzyl bromide at the more substituted site via lithium enolate gave poor yield. In this case an organozincate or an ammonium enolate also proved to be ineffective or not practical in terms of yield. Side chain elongation of the substituted cyclohexanone 13 through Grignard reaction, Wittig reaction, or Shappiro reaction did not proceed because of steric hindrance and side reactions. However, Stille coupling reaction via enol triflate produced the desired product 18 in high yield. The advanced intermediate 22, which was efficiently synthesized from 18, produced 24 instead of the desired product under a cationic olefin cyclization condition, indicating that the cyclization occurred in a stepwise mannervia the organomercury intermediate 23.