4,5,12,13-Tetrabromo[2.2]paracyclophane - A New Bis(aryne) Equivalent

The reaction of 2 with nBuLi at -78°C generates aryne intermediates within the aromatic rings of [2.2]paracyclophane which are trapped in Diels-Alder reactions with dienes like furan, 1,9-diphenylisobenzofuran, or cyclopentadiene. Reductive deoxygenation with low-valent titanium reagents or TMSI converts the adducts of furan and isobenzofuran into anti-[2.2]paracyclophanes 4 and 5, respectively. The reaction of two aryne intermediates with [2.2](2,5)furanophane (7) yields 8 with three [2.2]paracyclophane units arranged in a stair-like fashion; yet, in this compound the highly shielded oxygen atoms cannot be removed anymore by reduction

[2.2](4,7)Isobenzofuranophanes - Synthesis, Characterisation and Reactivity

The isomeric Diels-Alder adducts 3, obtained by cycloaddition of tetraphenylcyclopentadienone to the 4,5:12,13-bis-(oxanorbornadieno)[2.2]paracyclophanes syn,syn- and anti,-syn-2[Note ][The stereochemical descriptors syn and anti refer to the orientation of the oxygen bridge in the oxabicyclo[2.2.1]heptadiene subunits with respect to the [2.2]paracyclophaneskeleton.], yield the unstable isobenzofuranophane 4 by consecutive extrusion of carbon monoxide and tetraphenylbenzene when heated to 180°C. The molecular ion of 4 was observed in the EI mass spectrum. The stable tetraphenyl-substituted analogue 10 was synthesized independently from the previously unknown 4,5,12,13-tetrabenzoyl[2.2]paracyclophane (9). UV/Vis as well as fluorescence spectra and an X-ray crystal structure analysis of 9 are reported

Palladium-Catalyzed Domino Coupling Reactions of Aryl Halides with Norbornene Derivatives - A Simple Route to Polycyclic Aromatic Compounds

Under palladium-catalysis, norbornene 1, dicyclopentadiene 10, norbornenol 13, and norbornenone 15 react with unsubstituted as well as substituted bromo- and iodobenzenes to give 1 : 3 coupling products with 4-aryl-9,10-dihydrophenanthrene units with up to 70% isolated yields. The structures of two such products 4a and 4e were proved by X-ray crystal structure analysis. 2-Bromothiophene 17 reacts with 1 and 10 to yield a mixture of 2 : 1 and 3 : 1 coupling products, while 3-iodopyridine 22a, 3-iodo-6-methylpyridine 22b and 4-iodopyridine 25 give only 2 : 1 coupling products with 5,6-dihydro-3,8-phenanthroline and 5,6-dihydro-2,9-phenanthroline units, respectively. Some new mechanistic insights into this interesting four-component domino coupling reaction are presented. The products can easily be transformed by photocyclization/dehydrogenation and/or flash vacuum pyrolysis to a variety of cyclopentadiene-anellated polycyclic aromatic compounds in very high yields. The reported sequence also presents the easiest access to benzo[e]pyrene