Functionalisation of the upper rim of calix[4]arene via alcoholysis and hydrosilylation reactions

Metalation of 5,17-dibromo-25,26,27,28-tetra propoxy calix[4]arene (1) with n-BuLi in THF at −78 °C gave organolithium reagent, which reacted with Me2HSiCl to give 5,17-bis(dimethylsilyl)-25,26,27,28-tetra propoxy calix[4]arene (2). The Si–H groups of calixarene 2 were treated with methanol, ethanol, propanol, butanol, pentanol, hexanol, 2-propanol and 2-methyl propanol in the presence of Karstedt catalyst (platinum(0)-1,3-divinyl-1,1,3,3-tetramethyl disiloxane complex, solution in xylene) to give the corresponding 5,17-bis(alkoxydimethylsilyl)-25,26,27,28-tetra propoxy calix[4]arene (3). Moreover, calixarene 2 was easily functionalized with a variety of alkenes using Karstedt catalyst to give the corresponding organosilylated calix[4]arene (4).

Graphical abstractMetalation of calixarene 1 with n-BuLi in THF at −78 °C gave organolithium reagent, which reacted with Me2HSiCl to give calixarene 2. The Si–H groups of calixarene 2 were treated with various alcohols in the presence of Karstedt catalyst to give the corresponding calixarene 3. Calixarene 2 was functionalized with a variety of alkenes using Karstedt catalyst to give the corresponding organosilylated calixarene 4.Figure optionsDownload full-size imageDownload as PowerPoint slide