Calix[4]arene Derivatives Monosubstituted at All Four Methylene Bridges

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.