Synthesis, conformation, and binding properties of resorcarene tetrasulfonates. Asymmetric reorganization of pendant sulfonyl groups via intramolecular S=O---H-O hydrogen bonds

The regioselective reaction of resorcarene octaols 1 with 4 equiv of arylsu lfonyl chlorides and Et3N in MeCN gives in 30-60% yield the C-2v symmetrica l tetrasulfonates 3. The mild electrophilic substitution (aminomethylation, bromination) of resorcarene tetrasulfonates 3 and tetraphosphates 2 takes place only in the 2-positions of unsubstituted resorcinol rings yielding di stally disubstituted resorcarenes 4. The acylation of hydroxy groups in com pounds 2 and 3 gives C-2v symmetrical octaesters 5 including large resorcar ene tetracrown-ethers. In the minimized boat conformation of tetrasulfonate s 3 the two unsubstituted resorcinol rings are vertical and the sulfonyl fr agments are arranged in a C-2 symmetrical manner via intramolecular S=O- - -H-O hydrogen bonds. This structure is proved by NMR and IR spectroscopy. I n the case of tetrasulfonate 3c the two enantiomeric conformations intercon vert in CDCl3 with Delta G* = 11.6 kcal/mol. This is in agreement with the Delta E* value predicted by molecular mechanics in vacuo.