The Wurtz—Fittig Reaction in the Preparation of C-Silylated Calixarenes.

The Wurtz−Fittig reaction of tetraiodo calixarene 3 with Na/Me3SiCl in DME gave a mixture of tetrakis- and tris-silylated calixarenes (6 and 7). Tris(silyl) calixarene 7 was assigned the flattened cone conformation. A model study using p-bromoanisole and p-iodoanisole with Na/Me3SiCl gave the best results with p-bromoanisole in toluene. Attempts to extend this reaction to the tetrabromo calixarene 4 resulted in slow reactions giving mixtures of products. However, the Wurtz−Fittig reaction of the bromo benzyloxycalixarene 5 was faster, giving the debenzylated silyl ether 12.