Planar tridentate Lewis acids were synthesised by hydrosilylation reactions of triethynylbenzene with chlorosilanes. Hydrogenation of the rigid triethynylbenzene using hydrogen in the presence of Lindlar's catalyst resulted in the formation of trivinylbenzene. The hydrosilylation of this compound enabled the synthesis of flexible tridentate Lewis acids with SiClMe 2 and SiCl 2 Me, SiCl 3 groups. In order to increase the acidity, the [a] 2533 Scheme 2. Synthesis of 1,3,5-tris[(trimethylsilyl)ethynyl]benzene by Sonogashira cross-coupling reaction of 1,3,5-tribromobenzene and subsequent deprotection to 1,3,5-triethynylbenzene. Reagents and conditions: i) 1. TMSacetylene, I Pr 2 NH, CuI, PdCl 2 (PPh 3 ) 2 , reflux, 1 d; 2. aq. workup, 91 %; ii) THF, EtOH, 1 M NaOH, room temp., 1 d, 80 %.Scheme 3. Lindlar reduction of 1,3,5-trithynylbenzene and determination of conversion using GC-MS analysis after 18 h reaction time. Reagents and conditions: i) 1. EtOAc, Lindlar catalyst, quinoline, H 2 , room temp., 18 h; 2. aq. workup, 62 %.The gas chromatogram shows the presence of three other compounds resulting from further reduction of the double bonds in 3. Shorter reaction times, however, lead to incomplete Eur.

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Tridentate Lewis acids with aligned functions were synthesized based on the rigid framework hexadehydrotribenzo[12]annulene. The backbone and its fluorinated analogue were synthesised in one‐pot syntheses, with alkyne deprotection and Sonogashira cross coupling reaction being carried out in one step. Hydrosilylation of the annulene with chlorohydrosilanes proceeded highly selectively and afforded rigid poly‐Lewis acids with three SiCl3 or SiCl2Me substituents perfectly oriented to one side of the molecule in a single step. The progress of hydrosilylation was investigated by time‐correlated NMR spectroscopic studies. The crystal structures show that the framework is symmetrically functionalised and the silyl substituents are aligned in one direction. To increase the acidity of the Lewis acids the chlorosilyl substituents were fluorinated with SbF3. Further investigation of hydrometallation reactions (M=B, Al, Ga, Sn) did not lead to corresponding structures.

New triptycene derivatives have been synthesised based on the cycloaddition between 1,8‐bis[(trifluoromethanesulfonyl)‐oxy]anthracene as well as 1,8‐bis[(trimethylsilyl)ethynyl]anthracene and p‐benzoquinone. The resulting triptycenequinones were the key compounds for further functionalisation of the triptycene backbone, which were completely characterised by multinuclear NMR spectroscopy, mass spectrometry and X‐ray diffraction experiments. The aim was to substitute the triptycene backbone in positions 1, 8, 13 and 16 to avoid the formation of mixtures of syn‐ and anti‐isomers of trisubstituted triptycenes. Based on the ditriflate‐substituted triptycenequinone triptycene 1,8,13,16‐tetratriflate was synthesised and reacted with alkynyl compounds in cross‐coupling reactions. In further experiments the alkynyl‐substituted triptycene to quinone was directly reacted with lithiated trimethylsilylacetylene or was initially reduced, consequently functionalised with triflate groups and reacted in Sonogashira cross‐coupling reactions. It was found that both reaction pathways generate the anti‐substituted product in position 16 as main product.