Columbus Ishay, Biali Silvio E
Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
J Org Chem. 2008 Apr 4;73(7):2598-606. doi: 10.1021/jo702474n. Epub 2008 Mar 1.
The scope of the reaction of the tetrabromocalixarene derivative 2b with alcohols under solvolytic conditions in trifluoroethanol (TFE) or hexafluoroisopropanol (HFIP) was explored. The reaction proceeded readily with MeOH, EtOH, n-PrOH, ethylene glycol and i-PrOH affording preferentially the rccc isomer of the tetrasubstituted product. The methoxy derivative 6a undergoes isomerization upon attempted recrystallization from CHCl3/MeOH and its rcct and rctt forms were characterized by X-ray crystallography. Incorporation of hydroxy groups on the bridges was accomplished via solvolysis in AcOH, followed by LiAlH4 reduction of the acetoxy groups. Reaction of the tetra-(2-methylfuranyl)calixarene derivative 11 with benzyne followed by deoxygenation with Me3SiCl/NaI afforded in low yield the tetra-(4-methylnaphthyl)calix[4]arene derivative 12. Reaction of de-tert-butylated tetrabromo derivative 2a with m-xylene in HFIP followed by methylation of the crude product afforded the tetraxylyl derivative 14.
研究了四溴杯芳烃衍生物2b在三氟乙醇（TFE）或六氟异丙醇（HFIP）的溶剂解条件下与醇类的反应范围。该反应与甲醇、乙醇、正丙醇、乙二醇和异丙醇很容易进行，优先得到四取代产物的rccc异构体。甲氧基衍生物6a在尝试从CHCl₃/甲醇中重结晶时发生异构化，其rcct和rctt形式通过X射线晶体学进行了表征。通过在醋酸中进行溶剂解，然后用氢化铝锂还原乙酰氧基，在桥上引入羟基。四（2-甲基呋喃基）杯芳烃衍生物11与苯炔反应，然后用三甲基氯硅烷/碘化钠脱氧，以低产率得到四（4-甲基萘基）杯[4]芳烃衍生物12。脱叔丁基四溴衍生物2a与间二甲苯在HFIP中反应，然后对粗产物进行甲基化，得到四二甲苯基衍生物14。
