Calix[4]arenes with Two Different Chemical Modifications at the Bridges

Hexabromocalix[4]arene derivatives (3a and 3b) possessing pairs of dibromomethylene and bromomethylene groups located at distal or proximal positions of the calix scaffold were prepared via photochemical bromination of tetramethoxycalix[4]arene. The dibromomethylene groups undergo hydrolysis to afford calix[4]arenes possessing pairs of carbonyl groups and bromomethylene groups located at distal or proximal bridges (4a and 4b, respectively). The bromomethylene groups of 4 undergo reactions with nucleophiles under SN1 conditions to afford a wide array of derivatives possessing two different chemical modifications at the bridges.通过对四甲氧基杯[4]芳烃（tetramethoxycalix[4]arene）进行光化学溴化反应，成功制备得到六溴代杯[4]芳烃（Hexabromocalix[4]arene）衍生物3a与3b，该类衍生物的杯芳烃骨架的远端或近端位置分别带有由二溴亚甲基（dibromomethylene）与溴亚甲基（bromomethylene）组成的基团对。二溴亚甲基基团可发生水解反应，得到在桥链上带有羰基（carbonyl groups）与溴亚甲基基团对的杯[4]芳烃衍生物4a与4b，其中4a与4b分别对应远端与近端的取代模式。衍生物4中的溴亚甲基基团可在单分子亲核取代（SN1）反应条件下与亲核试剂（nucleophiles）发生反应，从而得到一系列在桥链上带有两种不同化学修饰基团的衍生物。