Synthesis and conformational studies of pentahydroxy[2.1.2.1.1]‐ and hexahydroxy [2.1.1.1.1.1]metacyclophanes

Base‐catalyzed condensation of 1,2‐bis[5‐ tert ‐butyl‐3‐(5‐ tert ‐butylsalicyl)‐2‐hydroxyphenyl]ethane ( 8 ) with formaldehyde in xylene affords a novel ethylene‐bridged calixarene‐analogous macrocyclic metacyclophane. However, not the desired 2 has been obtained. Instead, the novel macrocyclic compounds pentahydroxy[2.1.2.1.1]‐ ( 9 ) and hexahydroxy‐[2.1.1.1.1.1]metacyclophane ( 10 ) have been isolated in 35 and 25% yields, respectively. The mechanism for the above disproportionation occurring during the base‐catalyzed condensation of 8 to afford these macrocyclic metacyclophanes and their 1 H‐NMR spectral behavior are discussed.