NOVEL BICYCLIC CHIRAL CROWN ETHERS HAVING A p-XYLENEDIOXY UNIT WITH INPROVED COMPLEX STABILITY AND RATE-ENHANCEMENT IN THE INTRA-COMPLEX THIOLYSIS OF α-AMINO ACID ESTER SALTS

抄録

Novel bicyclic chiral crown ethers having an α, α'-p-xylenedioxy unit were synthesized. Crown dithiol 1 with a p-xylenedioxy bridge-structure perfomed intra-complex thiolysis with α-amino acid p-nitrophenyl ester HBr salts much faster than the corresponding dithiol 3 without the bridge-structure. A ¹H-NMR study suggested that the increased rate of intracomplex thiolysis is due to increased stability of the intermediary complex during the reaction.