Identifier: TDX:3146
Authors: Stoica, Otilia Violeta
Abstract:
This Doctoral Thesis covers the design of novel strategies for the synthesis of polycyclic aromatic hydrocarbons, such as acenes and their analogues. For instance, a new iterative synthesis was elaborated for the preparation of higher unsubstituted hydroacenes, based on our previously developed gold(I)-catalyzed formal [4+2] cycloaddition of aryl-tethered 1,7-tetraenynes, and enabled the formation of unprecedented hydroacenes, from tridecacene-H8 to heptadecacene-H10. The Au(111) surface-assisted dehydrogenation of the former precursor afforded the parent tridecacene, the longest acene known until now. The precursors of acene derivatives belonging to diverse categories, such as indacenes, cyclobutadiene-containing acenes or heteroacenes have been acquired by applying our gold(I)-catalyzed formal [4+2] cycloaddition to newly developed 1,7-enynes. The surface-assisted formation of the parent acenes has already been investigated or is currently ongoing. Two analogues from the first category, s-indaceno[1,2-b:5,6-b’]ditetracene and as-indaceno[2,3-b:6,7-b’]ditetracene, were obtained through cycloaddition of a bis-dihydrotetracene precursor on a Au(111) surface. The latter indacene derivative was found to undergo an outstanding intermolecular cycloaddition, rendering T-shaped molecules. The reaction was also successful when pentacene and octacene were employed as dienophiles. Finally, the Rh(III)-catalyzed ortho C–H alkynylation of aromatic aldehydes was investigated in order to obtain new versatile building blocks for the synthesis of polyarenes. Enabled by the formation of an imine as transient directing group, this transformation provided a wide variety range of mono- and di-alkynylated products. The acquired ynals were then successfully engaged in the preparation of substituted dibenzopentalenes, isoquinolines, indoles and indolines.
Repositori URV