Toward the synthesis of an aromatic belt

Vermeij, Rudolf J. (2001) Toward the synthesis of an aromatic belt. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

The work described in this thesis deals mainly with the application of the valence isomerization-dehydrogenation (VID) approach, previously developed by our group, to the synthesis of pyrenophanes with extended aromatic surfaces. As ultimate goal a fully aromatic "Vögtle" belt is proposed. -- Key intermediates for the synthesis of pyrenophanes via the VID approach are syn -2,11-dithia[3.3]metacyclophanes. In Chapter 2 the results of a study of the bridge conformational behavior of these compounds is discussed. This behavior is correlated with Hammett's constant (σm ) of the substituents in the 6- and 15-positions. The effect of the solvent is discussed and the study is completed with a DNMR study on several of the 6,15-disubstituted syn -2,11-dithia[3.3]metacyclophanes. -- In Chapter 3, a synthetic effort toward the synthesis of a pyrenophane with two para -phenylene units in the tether is described. In this case the VID methodology fails to give the desired pyrenophane. -- A straightforward synthetic plan for the synthesis of a Vögtle belt is described in Chapter 4. The synthesis stalled due to unavoidable side reactions during ring contraction of an advanced intermediate. -- The synthesis of pyrenophanes with one phenylene unit in the tether is described in Chapter 5. For two such pyrenophanes, [2]paracyclo[2](2,7)pyrenophane and [2]metacyclo[2](2,7)pyrenophane, a successful synthesis is reported, as well as their X-ray crystal structures. In both compounds the tether forces the pyrene unit to adopt a non-planar geometry and a spoons-like orientation of the aromatic decks is observed.

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