NMR CONFORMATIONAL STUDIES OF TETRAALKYLATED DIHOMOOXACALIX[4]ARENES

摘要

Four tetraethers (methyl, ethyl, ally] and benzyl) of p-tert-butyldihomooxacalix[4] arene were synthesized and their conformational behaviour studied by means of variable temperature H-1 NMR, including the determination of coalescence temperatures and Delta G(dagger). It was shown that the methyl ether still has some conformational mobility at -100 degrees C, the ethyl ether displays a fixed conformation at -20 degrees C and the other two derivatives are conformationally rigid at room temperature. The conformations obtained are the 1,2-alternate B and cone, depending on the derivative formed. (C) 1997 Elsevier Science Ltd. [References: 22]