Die gezielte Synthese von Catena‐Verbindungen, VIII. Umwandlung einer Triansa‐Verbindung in eine Catena‐Verbindung

Abstract

Auf Grund von Modelluntersuchungen wird erstmals die gezielte Synthese einer Catena-Verbindung (11) verwirklicht. Aus 11 werden die Catena-Verbindungen 12-14 dargestellt.Die I Rund UV-Spektren und das chromatographische Verhalten der Catena-Verbindungen und der sie aufbauenden makrocyclischen Partner werden verglichen und zusarnmen mit der Molekulargewichtsbestimmung zum Konstitutionsbeweis herangezogen.Die Synthese einer Diansa-Verbindung des 5-Amino-4.6-dipropyl-1.3-benzodioxols und ihre Aufspaltung in den aromatischen Kern und den Makroheterocyclus ~ bestehend aus den beiden Ketten des doppelhenkligen Systems mit dern Stickstoffatom ~ wurden schon friiher beschrieben3.4). Aufbauend auf Erfahrungen dieser Modelluntersuchungen war beabsichtigt, die intraanular verknupfte Triansa-Verbindung 6a darzustellen und sie anschlieRend durch Spalten der C -0 -und C-N-Bindungen zwischen dem aromatischen Kern mit der Polymethylenkette und dem Makroheterocyclus in eine Catena-Verbindung umzuwandeln L4).

Attempted [2]Catenane Synthesis via a Quasi[1]catenane by a Templated Backfolding Strategy

“…[2] Inspired by the landmark paper by Schill, we report here our efforts to combine the best of both worlds to arrive at [2]catenanes via quasi[1]-catenane 2 by introducing scissile bonds at the connecting tetrahedral carbon atom. Figure 1 illustrates a comparison of the design of the two quasi [1]catenanes differing in replacing the permanent central fluorene moiety reported before by a rigid cyclic ketal linkage based on L-(+)-tartaric acid in the current communication. This cyclic ketal ensures the desired perpendicular arrangement of the ring and thread fragments and is acid labile, thus allowing hydrolysis during the final acidolytic cleavage step.…”

“…Back in 1967 Schill reported one of the first [2]catenane syntheses using a covalent approach. [1] Crucial in his approach was the use of a cyclic ketal as motif for preorganization of the ring fragment, ensuring a perpendicular arrangement of the two linear ring precursors before ring closure (see Scheme 1). Scheme 1.…”

“…Recently, we reported a strategy using the perpendicular arrangement of a tetrahedral carbon atom for the synthesis of cursors and spatially directs the sterically congested backfolding macrocyclizations that are required to give a quasi [1]catenane. So far, we are unable to hydrolyze the cyclic ketal to liberate the [2]catenane.…”

“…So far, we are unable to hydrolyze the cyclic ketal to liberate the [2]catenane. bicyclic molecule 1 showing an inverted spiro architecture, coined as a quasi [1]catenane (see Figure 1). [2] Inspired by the landmark paper by Schill, we report here our efforts to combine the best of both worlds to arrive at [2]catenanes via quasi[1]-catenane 2 by introducing scissile bonds at the connecting tetrahedral carbon atom.…”

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Abstract: A templated backfolding concept to construct a [2]catenane was attempted via a quasi [1]catenane showing an inverted spiro geometry. The template is covalently connected to the ketal-connected semi-perpendicular-arranged linear pre-

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