Selective Synthesis and Isolation of All Possible Conformational Isomers of Proximally Para-Disubstituted Calix[4]arene
作者:Shoichi Shimizu、Akihiro Moriyama、Katsuyuki Kito、Yasuyuki Sasaki
DOI:10.1021/jo0267293
日期:2003.3.1
All six possible conformational isomers of the proximally p-dibrominated calix[4]arene tetraalkyl ether, 1a-f*, were selectively synthesized by appropriate control of stereochemistry during di-O-alkylation reactions of 5,11-dibromocalix[4]arene syn-dialkyl ethers, namely, 5,11-dibromo-27,28-dihydroxy-25,26-dipropoxy-, 5,11-dibromo-25,26-dihydroxy-27,28-dipropoxy-, 5,11-dibromo-25,28-dihydroxy-26,27-propoxy-
近端对二溴化杯[4]芳烃四烷基醚1a-f *的所有六个可能的构象异构体,通过适当控制立体化学在5,11-二溴杯[4]芳烃的二-O-烷基化反应中选择性合成-二烷基醚,即5,11-二溴-27,28-二羟基-25,26-二丙氧基-,5,11-二溴-25,26-二羟基-27,28-二丙氧基-,5,11-二溴- 25,28-二羟基-26,27-丙氧基-和5,11-二溴-26,28-二羟基-25,27-二丙氧基杯[4]芳烃。它们的构象已通过(1)H和(13)C NMR光谱证实,并且对于1a而言是锥形的(u(Br)(Pr),u(Br)(Pr),u(H)(Pr),u(H) (Pr)),1b(u(Br)(Pr),d(Br)(Pr),u(H)(Pr),u(H)(Pr))和1d(u(Br)( Pr),u(Br)(Pr),u(H)(Pr),d(H)(Pr)),1c的1,2-交替(u(Br)(Pr),u(Br)(Pr