Facile Synthesis of Aluminum‐Bridged [3,3,3]Cyclophanes by Hydroalumination

The reaction of 1,3,5‐tris(3,3‐dimethyl‐1‐butinyl)benzene C6H3(C≡C–CMe3)3 with the dialkylaluminum hydrides HAl(CMe3)2 and HAl(CH2CMe3)2 gave the addition of one Al–H bond to each C–C triple bond (hydroalumination). Spontaneous condensation by the release of the corresponding trialkylaluminum derivatives afforded [3,3,3]cyclophane derivatives 6 and 7 in which three tricoordinate Al atoms are in the bridging positions between two functionalized benzene rings. The aluminum atoms behave as Lewis acids, and treatment with thf yielded adduct 6·3thf. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)