Takehiko Yamato, Yoshiyuki Saruwatari and Masashi Yasumatsu
Base-catalysed condensation of 1,3-bis(5-tert-butyl-2-hydroxyphenyl)propane 5 with formaldehyde in xylene has been carried out to form the novel propane-bridged calixarene-type macrocyclic compound, tetrahydroxy[3.1.3.1]metacyclophane 6. The optimum yield (90%) of 6 is obtained with NaOH as the base, the use of other alkali-metal hydroxides giving lower yields. AlCl3–MeNO2-catalysed trans-tert-butylation of 6 in benzene affords 7 in 80% yield. Intramolecular hydrogen bonding has been observed in the tetraols 6 and 7 as comparable to calix[4]arene. Methylation of 7 with MeI affords the tetramethoxy derivative 11a. The stability of multi-membered carbon skeletons permits the interconversion of functional groups at the lower and upper rims without special regard to ring-opening side-reactions on the upper rim. For example, the introduction of Br, formyl and acetyl substituents has been achieved by electrophilic aromatic substitution of the tetramethoxy derivative 11a. The 1H NMR spectral behaviour of these macrocyclic metacyclophanes is also discussed.