T. Yamato et al., SYNTHESIS AND CONFORMATIONAL STUDIES OF NOVEL CALIXARENE-ANALOGOUS MACROCYCLIC [3.1.1]METACYCLOPHANES, Liebigs Annalen, (7), 1997, pp. 1537-1544
Hydroxy[3.1.1]metacyclophane 4c, which is regarded as an unsymmetric o
r uncomplete ''homocalixarene'' bearing a propane bridge, has been syn
thesized using Nafion-H catalyzed cyclobenzylation. A novel ''pendulum
'' type motion steered by intramolecular hydrogen bonding has been obs
erved. Demethylation of compound 4c with BBr3 in methylene dichloride
was carried out at room temperature for 3 h to afford the dihydroxy[3.
1.1]metacyclophane 4b in 74% yield along with the triol 4a in 25% yiel
d. Triol 4a was tri-O-alkylated xith methyl iodide in the presence of
NaH to yield partial-cone conformer 4d in quantitative yield. Similarl
y, a significant amount of partial-cone conformer 5 results in the cas
e of O-alkylation of 4a with N,N-diethylchloroacetamide. H-1-NMR titra
tion of partial-cone amide 5 with NaSCN clearly demonstrates that a 1:
1 complex is formed which is stable on the NMR time scale.