An approach to calix[6]cryptands with bridgehead carbon atom: Stabilized in- and out- stereoisomers

摘要

A new approach to cap 1,3,5-trimethyloxy-p-tert-butyl calix[6]arene with 1,1,1-tri(tosyloxyethoxyethoxymethyl)propane to form a pair of separable stabilized in- and out- calix[6]cryptands was reported. After heating 5a or 5b at 280 degrees C, the interconversiqn between them was not detected by TLC, which provides a direct and non-spectral methodology to obtain unambiguous evidence for the ring immobilization in calix[6]arenes with stereoisomers. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 20]