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23 Apr 2015 Abstract. A single-strand arylene–vinylene precursor containing four phenylene and three naphthylene units linked together with six vinylene spacers undergoes helical folding via sextuple photocyclization to give a [16]helicene core in a single step. The phenylene and naphthylene units are arranged in
Abstract. An improved procedure has been developed for photodehydrocyclization of stilbenes for the synthesis of phenanthrenes and helicenes. This procedure involves the use of THF as a scavenger of hydriodic acid produced during iodine mediated photodehydrocyclization. The use of THF is advantageous due to its
3 Feb 2017 destinee au depot et a la diffusion de documents thesis and Chiroptical Properties of Hexa-, Octa-, and Deca-azaborahelicenes: Influence of Helicene . Results and Discussion. Synthesis and characterization of m azabora[n]helicenes (n. = 6, 8, platina[10]helicene. In 2010, our group reported the first
5 Jan 2015 A facile synthesis of functionalized 7,8-diaza[5]helicenes through an oxidative ring-closure of 1,1'-binaphthalene-2,2'-diamines (BINAMs) . ring-closure of BINAMs using 1a as the model substrate (Table 1, for the full details of the screening of reaction conditions, see Supporting Information File 1).
Herein we propose a general mechanism for the racemization of [n]helicenes up to n = 24. It is a concerted process for n = 4–7, but a multi-step mechanism is followed for n ? 8, involving 2n ? 14 intermediates. The changes in the barriers are a delicate consequence of the steric hindrance and the ?-interacti.
The synthesis and properties of a new ?-extended double [6]helicene 2 and a dithia[6]helicene 3 are described. Compared to the previously reported parent double-helicene molecule 1, the introduction of n-butyl groups successfully improved the solubility, which allowed an experimental investigation into the e.
19 May 2017 Three-bladed propeller-shaped triple [5]helicene was synthesized using eliminative and oxidative photocyclization reactions, which proceeded in 37 and 63% yields, respectively. Chromatographic purification gave a mixture of diastereomers, and the PPM and PMM isomers were gradually converted to the
28 Feb 2014 With 2,7-di-tert-butyl-pyren-4-yl or chrysen-6-yl as the aryl, photocyclodehydrogenation of the diarylmaleimides yields substituted helicenes which can be reduced to stable anions. The helicenes combine bathochromically shifted absorption with hypsochromically shifted fluorescence with respect to their
8 Nov 2016 Rational Design and Synthesis of [5]Helicene-Derived Phosphine Ligands and Their Application in Pd-Catalyzed Asymmetric Reactions Thus, helicenes can be utilized them a broad range of applications in chiral materials, in the chiral recognition of biomolecules, and in asymmetric PDF files. 1.
26 Sep 2016 Abstract. We report two new helicenes derived from the double fusion of an acene with two perylene diimide (PDI) subunits. These PDI-helicene homologs exhibit very different structural and electronic properties, despite differing by only a single ring in the link between the PDI units. The shorter inter-PDI

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February 2018