Often stoichiometric amounts of gold
find use in materials science;
occasionally gold is even used as a support. This review discusses
the contributions of gold catalysis, both homogeneous and heterogeneous,
to the field of materials science. One topic is the synthesis of polymers,
including nanowires and polyesters, the postcyclization of polymers,
polymerization by cyclopropanation, and gold-catalyzed radical polymerization
reactions. Other topics are dyes, phosphonium salts, and a wide range
of extended conjugated π-systems, the latter ranging from acenes,
pentalene derivatives, and different heterocyclic π-systems
to fascinating applications in the synthesis of helical anellated
aromatic molecules. The existing contributions clearly demonstrate
the potential of gold catalysis for significant future impulses for
the field of materials science.
Herein we describe a modular, convergent synthesis of substituted benzo[a]benzo[6,7]‐indolo[2,3‐h]carbazoles (BBICZs) using a bidirectional gold‐catalyzed cyclization reaction as a key step. A building block strategy enabled the easy variation of substituents at different positions of the core structure and a general analysis of substitution effects on the materials properties of the target compounds. All BBICZs were fully characterized and their optical and electronic properties were studied experimentally as well as by computational methods. Organic thin‐film transistors based on eight selected derivatives were fabricated by vacuum deposition and charge‐carrier mobilities up to 1 cm2/Vs were measured.
Herein we describe a gold‐catalyzed bidirectional synthesis of N‐heteropolycyclic compounds bearing carbazole moieties – namely π‐extended benzodicarbazoles and π‐extended indolocarbazoles. Overall, four previously unknown core structures were synthesized. This approach is convergent, modular and the gold‐catalyzed key step comprises of a cascade reaction starting from stable di‐azido compounds. The obtained molecules were fully characterized and their optical and electronic properties as well as their performance in organic thin‐film transistors generated by vacuum deposition were studied. Charge‐carrier mobilities of up to 0.3 cm2/Vs were measured.
Diynes bearing one terminal and one triarylmethyl-substituted alkyne were converted into complex benzofluorenone derivatives via a one-pot process involving a gold-catalyzed step followed by a photocyclization/oxidation. In the first step an Noxide was used to position-selectively generate an a-oxo carbenoid at the terminal alkyne which after a regioselective 1,6-carbene transfer along the tethered tritylalkyne and a subsequent aryl 1,2-shift furnished tetraphenylethylene-like derivatives. These intermediates were successfully transformed to fluorenones via oxidative photocyclization.
Herein, we describe a gold-catalyzed cascade cyclization of Boc-protected benzylamines bearing two tethered alkyne moieties in a domino reaction initiated by a 6endo-dig cyclization. The reaction was screened intensively, and the scope was explored, resulting in nine new Bocprotected dihydrobenzo[c]phenanthridines with yields of up to 98 %; even a π-extension and two bidirectional approaches were successful. Furthermore, thermal cleavage of the Boc group and subsequent oxidation gave substituted benzo [c] phenanthridines in up to quantitative yields. Two bidirectional approaches under the optimized conditions were successful, and the resulting π-extended molecules were tested as organic semiconductors in organic thin-film transistors.
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